Channel quality report processes, circuits and systems

ABSTRACT

An electronic device includes a first circuit ( 111 ) operable to generate at least a first and a second channel quality indicator (CQI) vector associated with a plurality of subbands for each of at least first and second spatial codewords respectively and generate a first and a second reference CQI for the first and second spatial codewords, and operable to generate a first and a second differential subbands CQI vector for each spatial codeword and generate a differential between the second reference CQI and the first reference CQI, and further operable to form a CQI report derived from the first and the second differential subbands CQI vector for each spatial codeword as well as the differential between the second reference CQI and the first reference CQI; and a second circuit ( 113 ) operable to initiate transmission of a signal communicating the CQI report. Other electronic devices, processes and systems are also disclosed.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a Continuation of application Ser. No. 12/327,463filed Dec. 3, 2008, which claims the benefit under 35 U.S.C. 119(e) ofU.S. Provisional Application No. 61/013,380 entitled “CQI Feedback forMIMO-OFDMA Systems” filed on Dec. 13, 2007, and which is incorporatedherein by reference in its entirety.

This application is a Continuation of application Ser. No. 12/327,463filed Dec. 3, 2008, which claims the benefit under 35 U.S.C. 119(e) ofU.S. Provisional Application No. 61/019,802 (TI-65716PS1) entitled “CQIFeedback for MIMO-OFDMA Systems (update)” filed on Jan. 8, 2008, andwhich is incorporated herein by reference in its entirety.

This application is a Continuation of application Ser. No. 12/327,463filed Dec. 3, 2008, which claims the benefit under 35 U.S.C. 120 of U.S.patent application “Precoding Matrix Feedback Processes, Circuits andSystems,” Ser. No. 12/188,767 (TI-65218) filed Aug. 8, 2008, and whichis incorporated herein by reference in its entirety.

U.S. Patent Application Publication 2008-0013610 “CQI Feedback For MIMODeployments” of Jan. 17, 2008, and corresponding U.S. patent applicationSer. No. 11/759,221 (TI-62585) fled Jun. 6, 2007, are each incorporatedherein by reference in their entirety.

U.S. Patent Application Publication 2008-0207135 “CQI Feedback for OFDMASystems” of Aug. 28, 2008, and corresponding U.S. patent applicationSer. No. 12/036,066 (TI-64201) filed Feb. 22, 2008, are eachincorporated herein by reference in their entirety, and to the extentapplicable this application claims the benefit under 35 U.S.C. 120thereof.

The present application is related to U.S. Provisional Application No.60/974,345 (TI-65393PS) entitled “Scanning-based CQI feedback for OFDMA”filed on Sep. 21, 2007, and which is incorporated herein by reference inits entirety.

This application is a Continuation of application Ser. No. 12/327,463filed Dec. 3, 2008, which claims the benefit under 35 U.S.C. 120 of U.S.patent application “Differential CQI for OFDMA Systems,” Ser. No.12/254,738 (TI-65514) filed Oct. 20, 2008, and which is incorporatedherein by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

COPYRIGHT NOTIFICATION

Portions of this patent application contain materials that are subjectto copyright protection. The copyright owner has no objection to thefacsimile reproduction by anyone of the patent document, or the patentdisclosure, as it appears in the United States Patent and TrademarkOffice, but otherwise reserves all copyright rights whatsoever.

FIELD OF THE INVENTION

The present invention is directed, in general, to electronic circuitsfor supporting wireless communications, to various wireless systems, andto methods of operating the circuits and systems.

BACKGROUND OF THE INVENTION

A wireless network may employ orthogonal frequency division multiplexing(OFDM) or orthogonal frequency division multiple access (OFDMA). In acellular wireless network, each cell employs a base station (designatedby Node B or eNB) that communicates with user equipment (UE), such as acell phone, a laptop, or a PDA. Base station eNB transmits referencesignals or pilot signals to UE, which generates a channel estimate basedon the reference signal, has impacted by interference and noise. Thesystem bandwidth is divided into frequency-domain groups or subbandsthat encompass resource blocks RBs according to group size or subbandsize. An RB is the smallest allocation unit available in terms offrequency granularity allocated to UE by a base station schedulermodule.

UE determines a channel quality indicator (CQI) for each RB or for eachsubband based on the channel estimation. The CQI metric is suitably asignal to interference noise ratio (SINR) after detection, the index toa supportable modulation and coding scheme, the index to a supportablecode rate, a channel throughput measure, or other quality measure. UEfeeds back the CQI for each subband or RB to eNB. More favorable CQIpermits a higher data transfer rate of data streams by eNB to UE.

By using multiple transmit and multiple receive antennas with transmitpre-coding in a multi-input multi-output (MIMO) system, improvedthroughput and/or robustness are obtained. Pre-coding in a MIMO systeminvolves determining and applying a linear or complex lineartransformation for each RB to the data stream(s) allocated to the RB byan eNB scheduler prior to transmission via physical antennas. The numberof independent data streams (number of spatial codewords) is termed thetransmission rank. Denoting a P×R precoding matrix for each downlink RBas PM and the R independent data streams as an R-dimensional vector s,the transmitted signal via P physical antennas (P>=R) is written as:x=PM s. For a frequency division duplex FDD system where the uplink anddownlink channels are not reciprocal, precoding matrices to contributeto the matrix PM are efficiently chosen at UE by indexing to apre-determined set of matrices (pre-coding codebook). Based on thechannel estimate, UE feeds back to the base station for each of itssubbands or RBs, the precoding matrix index (PMI) and the CQI expectedto occur when eNB uses the indexed precoding matrix to transmit data inan RB in a given subband.

A high level of operational overhead and uplink bandwidth is believed tohave hitherto been involved when each of many UEs deliver feedback aboutmany subbands to eNB. This can undesirably increase system processingdelays and dissipation of power and energy which is of particularconcern in mobile handset forms of UE. Accordingly, further ways ofreducing the amount of communications feedback between user equipmentand base station are desirable.

SUMMARY OF THE INVENTION

A form of the invention involves an electronic device that includes afirst circuit operable to generate at least a first and a second channelquality indicator (CQI) vector associated with a plurality of subbandsfor each of at least first and second spatial codewords respectively andgenerate a first and a second reference CQI for the first and secondspatial codewords, and operable to generate a first and a seconddifferential subbands CQI vector for each spatial codeword and generatea differential between the second reference CQI and the first referenceCQI, and further operable to form a CQI report derived from the firstand the second differential subbands CQI vector for each spatialcodeword as well as the differential between the second reference CQIand the first reference CQI; and a second circuit operable to initiatetransmission of a signal communicating the CQI report.

Another form of the invention involves a CQI report scanning circuitincluding a first circuit operable to generate a CQI report derived fromat least a first and a second channel quality indicator (CQI) vectorassociated with a plurality of subbands for each of at least first andsecond spatial codewords respectively, and a second circuit operable toconfigurably establish a scanning pattern for the CQI report across thespatial codewords and subbands and to initiate transmission of a signalcommunicating the CQI report according to the configurably establishedscanning pattern.

A further form of the invention involves a channel quality indicator(CQI) reporting circuit including a first circuit operable to generateat least a first and a second channel quality indicator (CQI) vectorassociated with a plurality of subbands for each of at least first andsecond spatial codewords respectively and a first and a seconddifferential subbands CQI vector for each of the first and secondspatial codewords respectively, and further operable to generate a CQIreport based on a vector differential between the second differentialsubbands CQI vector and the first differential subbands CQI vector, anda second circuit operable to initiate transmission of a signalcommunicating the CQI report.

An additional form of the invention involves a MIMO wireless node formultiple-input, multiple-output (MIMO). The wireless node includes areceiver to receive at least one signal, each communicating a channelquality indicator (CQI) report for first and second spatial codewordsassociated with a user equipment wherein the CQI report is derived froma first reference CQI and a first and a second differential subbands CQIvector for each spatial codeword as well as a differential between asecond reference CQI and the first reference CQI. A processing circuitryis coupled to the receiver and operable to reconstruct a first andsecond subbands CQI vector from the at least one signal associated withthe CQI report.

Still another form of the invention involves a MIMO wireless node formultiple-input, multiple-output (MIMO). The wireless node includes areceiver to receive at least one signal, each communicating a compressedchannel quality indicator (CQI) report associated with a user equipmentfor spatial codewords and subbands, and a processing circuitry coupledto the receiver and operable for reconstructing at least a first and asecond CQI vector from said at least one signal according to aconfigurably established scanning pattern for processing the CQI reportacross the spatial codewords and subbands wherein each reconstructed CQIvector is associated with a plurality of subbands for each of at leastfirst and second spatial codewords respectively.

Another additional form of the invention involves a MIMO wireless nodefor multiple-input, multiple-output (MIMO). The wireless node includes areceiver to receive at least one signal, each communicating a channelquality indicator (CQI) report associated with a user equipment for atleast first and second spatial codewords and subbands. A processingcircuitry is coupled to the receiver and operable for reconstruction ofat least a first and a second CQI vector, associated with subbands foreach of the at least first and second spatial codewords respectively,from the CQI report including information based on a vector differentialbetween a second differential subbands CQI vector for the second spatialcodeword and a first differential subbands CQI vector for the firstspatial codeword.

Other forms of inventive electronic circuits, devices, processes andsystems are also disclosed and claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, reference isnow made to the following descriptions taken in conjunction with theaccompanying drawings, in which:

FIGS. 1 and 2 each provide a respective system block diagram of a MIMOOFDMA receiver and transmitter for UE or eNB improved as shown in theother Figures.

FIGS. 3 and 4 are each a frequency spectrum diagram, and FIG. 3 showsresource blocks (RBs) associated with respective sub-bands and ChannelQuality Indicator (CQI) values S₁-S₅, and FIG. 4 shows subbands withnumbers L₁ through L_(M) of resource blocks (RBs) associated withrespective Channel Quality Indicator (CQI) values S₁-S_(M).

FIG. 5 is a hypothetical graph of channel quality indicator CQI versusfrequency sub-bands, and FIG. 6 illustrates a CQI vector S=CQI_(r,j) ofCQI values generated by a UE and associated with the frequency sub-bandsj of FIG. 5 and various spatial streams or spatial codewords r.

FIGS. 7 and 8 are respectively a flow diagram of a UE process in FIG. 7having different CQI feedback or reporting modes, and an eNB process inFIG. 8 for establishing different CQI feedback modes and responding tothe CQI report.

FIG. 9 is a frequency versus time diagram of resource blocks RB of FIG.3 or FIG. 4 in OFDMA communication.

FIGS. 10-20 and 24A-31B are diagrams of spatial codewords (streams)versus subbands for different CQI reporting processes.

FIG. 10 shows quantization by codeword, and FIG. 11 shows a process thatgenerates pairwise differences across streams and quantizes differences.

FIG. 12 shows CQI wideband reporting for plural codewords, and FIG. 13further shows spatial differential encoding of a wideband CQI acrosscodewords.

FIG. 14 shows wideband CQI reporting combined with frequencydifferential CQI reporting for subbands on a codeword by codeword basis,and FIG. 15 further shows differential encoding of a wideband CQI acrosscodewords.

FIG. 16 shows is wideband CQI reporting, spatial differential encodingof a wideband CQI across codewords, frequency differential CQI reportingfor subbands for a first codeword, and differential encoding of CQI of asecond codeword spatially differentially encoded (Delta Delta) relativeto frequency differential encoding for the first codeword.

FIG. 17 shows CQI reporting for different codewords using pairwisedifferences in the frequency domain followed by quantization, and FIG.18 further shows the reference subband of the second codeword encodedspatially differentially with respect to the reference subband of thefirst codeword.

FIG. 19 shows CQI reporting for different codewords using pairwise CQIdifferences for adjacent sub-bands followed by quantization, and withthe reference subband of the second codeword encoded spatiallydifferentially with respect to the reference subband of the firstcodeword, and further having differential coding across codewords of thepairwise differences (Delta Delta).

FIG. 20 shows CQI reporting for different codewords using differencesrelative to a reference subband followed by quantization, and with thereference subband of the second codeword encoded spatiallydifferentially with respect to the reference subband of the firstcodeword, and further having differential coding across codewords ofdifferences relative to reference (Delta Delta).

FIGS. 21, 22, 23 are each a diagram of subbands in the frequency domain,where FIG. 21 shows Best-m CQI reporting of an average CQI for selectedsubbands and wideband CQI reporting for unselected subbands; FIG. 22shows Best-m CQI reporting of individual CQI for selected subbandsrespectively, and wideband CQI reporting for unselected subbands; andFIG. 23 shows individual reporting of CQI for each subband.

FIGS. 24A and 24B are each a diagram of subbands in the frequency domainfor different codewords showing Best-m frequency differential CQIreporting relative to a wideband CQI, and wideband CQI reporting forunselected subbands spatially differentially encoded across codewords,and in FIG. 24A the selected (Best-m) subbands have the same subbandindices across codewords, and in FIG. 24B the selected (Best-m) subbandshave different subband indices when compared across codewords.

FIGS. 25A and 25B are each a diagram of subbands in the frequency domainfor different codewords showing Best-m frequency differential averageCQI reporting relative to a wideband CQI for the first codeword,spatially differentially encoded frequency differential CQI for a secondcodeword (Delta Delta) relative to the frequency differential CQI forthe first codeword, and wideband CQI reporting for unselected subbandsspatially differentially encoded across codewords, and in FIG. 25A theselected (Best-m) subbands have the same subband indices acrosscodewords, and in FIG. 25B the selected (Best-m) subbands have differentsubband indices when compared across codewords.

FIGS. 26A and 26B are each a diagram of subbands in the frequency domainfor different codewords showing Best-m individual frequency differentialCQI reporting for selected subbands relative to an wideband CQI, andwideband CQI reporting for unselected subbands by codeword, and in FIG.26A the selected (Best-m) subbands have the same subband indices acrosscodewords, and in FIG. 26B the selected (Best-m) subbands have differentsubband indices when compared across codewords.

FIGS. 27A and 27B are each a diagram of subbands in the frequency domainfor different codewords showing Best-m individual frequency differentialCQI reporting for selected subbands relative to an wideband CQI, andwideband CQI reporting for unselected subbands spatially differentiallyencoded across codewords, and in FIG. 27A the selected (Best-m) subbandshave the same subband indices across codewords, and in FIG. 27B theselected (Best-m) subbands have different subband indices when comparedacross codewords.

FIGS. 28A and 28B are each a diagram of subbands in the frequency domainfor different codewords showing Best-m individual frequency differentialCQI reporting for selected subbands relative to an wideband CQI for thefirst codeword (Delta), individual spatial differential CQI for selectedsubbands of a second codeword relative to the individual CQI for theselected subbands of the first codeword (spatial Delta), and widebandCQI reporting for unselected subbands spatially differentially encodedacross codewords, and in FIG. 28A the selected (Best-m) subbands havethe same subband indices across codewords, and in FIG. 28B the selected(Best-m) subbands have different subband indices when compared acrosscodewords.

FIGS. 29A and 29B are each a diagram of subbands in the frequency domainfor different codewords, showing wideband CQI report for unselectedsubbands of the first codeword, wideband CQI report for unselectedsubbands of the second codeword encoded spatially differentially withrespect to the wideband CQI of the first codeword (spatial delta),best-m average CQI report for selected subbands of the first codeword,and best-m average CQI report for selected subbands of the secondcodeword encoded spatially differentially with respect to the best-maverage CQI of the first codeword (spatial delta), and in FIG. 29A wherethe selected (best-m) subbands have the same subband indices acrosscodewords, and in FIG. 298 where the selected (best-m) subbands havedifferent subband indices when compared across codewords.

FIGS. 30A and 30B are each a diagram of subbands in the frequency domainfor different codewords, showing wideband CQI report for unselectedsubbands of the first codeword, wideband CQI report for unselectedsubbands of the second codeword encoded spatially differentially withrespect to the wideband CQI of the first codeword (spatial delta),Best-m individual CQI report for each of the selected subbands of thefirst codeword, and Best-m individual CQI report for each of theselected subbands of the second codeword encoded spatiallydifferentially with respect to the Best-m individual CQI of thecorresponding subband of the first codeword (spatial delta), and in FIG.30A where the selected (Best-m) subbands have the same subband indicesacross codewords, and in FIG. 30B where the selected (Best-m) subbandshave different subband indices when compared across codewords.

FIGS. 31A and 31B are each a diagram of subbands in the frequency domainfor different codewords showing Best-m individual frequency differentialCQI reporting for selected subbands relative to an wideband CQI for thefirst codeword, spatially differentially encoded individual frequencydifferential CQI for a second codeword (Delta Delta) relative to theindividual frequency differential CQI for the first codeword, andwideband CQI reporting for unselected subbands spatially differentiallyencoded across codewords, and in FIG. 31A the selected (Best-m) subbandshave the same subband indices across codewords, and in FIG. 31B theselected (Best-m) subbands have different subband indices when comparedacross codewords.

FIGS. 32-37 are each a diagram of codewords versus subbands enumeratinga process sequence for scanning-based CQI reporting. FIG. 32 CQIreporting is in subband order, codeword by codeword. FIG. 33 CQIreporting is in codeword order, subband by subband. FIG. 34 CQIreporting is in mixed codeword and subband order. FIG. 35 CQI reportingis in subband order, codeword by codeword, wherein the number ofsubbands M varies with codeword index r.

FIG. 36 CQI reporting is across codewords wherein both the number ofsubbands M and the number of resource blocks per subband vary withcodeword index r. FIG. 37 CQI reporting is across codewords wherein thenumber of resource blocks per subband vary with subband index j.

FIGS. 38-41, 41A, 42, 42A are each a pair of side-by-side flow diagramsof a user equipment UE and a base station eNB.

FIGS. 38, 39, 40 show different process embodiments of Delta Delta CQIreporting processes in UE, and processes in eNB to reconstruct the CQIsfor subbands of codewords from the Delta Delta CQI report.

FIG. 41 shows a Best-m Average CQI reporting process in UE and a processto reconstruct the CQIs for selected subbands and unselected subbands ofcodewords from the Best-m CQI report for use by the eNB.

FIG. 41A shows a Best-m Average Delta Delta CQI reporting process in UEand a process to reconstruct the CQIs for selected subbands andunselected subbands of codewords from the Delta Delta CQI report for useby the eNB.

FIG. 42 shows a Best-m individual differential CQI reporting process inUE and a process to reconstruct the individual CQIs for selectedsubbands of codewords from the Best-m CQI report for use by the eNB.

FIG. 42A shows a Best-m Delta Delta individual differential CQIreporting process in UE and a process to reconstruct the individual CQIsfor selected subbands of codewords from the Best-m Delta Delta CQIreport for use by the eNB.

FIG. 43 is a flow diagram of a process for use in base station eNB toapply a scanning pattern and use a subband vector SV indicating selectedindividual subbands for Best-m CQI reporting involving multiplecodewords in a MIMO system.

Corresponding numerals refer to corresponding parts in the variousFigures of the drawing, except where the context may indicate otherwise.Some overlap of algebraic symbols with each other may occur, and thecontext makes their meaning clear.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1 illustrates a system diagram of a receiver 100 in an OFDMcommunications system. The receiver 100 is part of a mobile handset 1010or otherwise located in a telecommunication unit of fixed or mobiletype. The receiver 100 includes a receive portion 105 and a reporting orfeedback generation portion 110. The receive portion 105 includes anOFDM module 106 having Q OFDM demodulators (Q is at least one (1) andequals or exceeds the number P of antennas) coupled to correspondingreceive antenna(s), a MIMO detector 107, a QAM demodulator plusde-interleaver plus FEC decoding module 108 and a channel estimationmodule 109. The feedback portion 110 includes a precoding matrixselector 111, a channel quality indicator (CQI) computer 112, rankselector 114, and a feedback encoder 113.

The receive portion 105 in FIG. 1 receives data from a transmitter 150of FIG. 2 based on a precoding matrix selection that was determined bythe receiver 100 in FIG. 1 and fed back to the transmitter of FIG. 2. InFIG. 1, the OFDM module 106 demodulates the received data signals andprovides them to the MIMO detector 107, which employs channel estimation109 and precoding matrix information to further provide the receiveddata to the module 108 for further processing (namely QAM demodulation,de-interleaving, and FEC decoding). The channel estimation module 109employs previously transmitted channel estimation pilot signals togenerate the channel estimates for receiver 100. The precoding matrixinformation can be obtained via an additional downlink signalingembedded in the downlink control channel or in a reference signal.Alternatively, the receiver 100 can obtain the precoding matrixinformation from the previously selected precoding matrix. In addition,the two sources can also be used in conjunction with each other tofurther improve the accuracy.

In FIG. 1, the precoding matrix selector 111 determines the precodingmatrix selection for the data transmission based on thechannel/noise/interference estimates from block 109. This precodingmatrix operation occurs in tandem with rank selector 114 determinationof a preferred rank R for number of spatial code words to beaccommodated. CQI is calculated based on the selected precoding matrixor its index (PMI) in a PMI codebook. The precoding matrix selection andCQI are computed for the next time the user equipment UE of FIG. 1 isscheduled by the transmitter (e.g., a base station FIG. 2) to receivedata. In FIG. 1, the feedback encoder 113 then encodes the precodingmatrix selection and the CQI information and rank R and feeds them backseparately encoded to the transmitter before the data is transmitted. Inone embodiment, the precoding matrix selection is jointly encoded toachieve feedback transmission compression. For improved efficiency, theprecoding matrix selection and CQI are jointly encoded into onecodeword.

FIG. 2 illustrates a system diagram of a transmitter 150 such as for abase station eNB 1050 of FIG. 42 in an OFDM communication system. Thetransmitter 150 includes a transmit portion 155 and a feedback decodingportion 160. The transmit portion 155 includes a modulation and codingscheme (MCS) module 156, a pre-coder module 157 and an OFDM module 158having multiple OFDM modulators that feed corresponding transmitantennas. The feedback decoding portion 160 includes a receiver module166 and a decoder module 167.

The transmit portion 155 is employed to transmit data provided by theMCS module 156 to a receiver 100 based on pre-coding provided by thepre-coder module 157. The MCS module 156 takes codeword(s) and maps thecodeword(s) to the R layers or spatial streams, where R is thetransmission rank and at least one. Each codeword consists ofFEC-encoded, interleaved, and modulated information bits. The selectedmodulation and coding rate for each codeword are derived from the CQI. Ahigher CQI implies that a higher data rate may be used. The pre-codermodule 157 employs a precoding matrix selection obtained from thefeedback decoding portion 160, wherein the precoding matrix selectioncorresponds to a grouping of frequency-domain resource blocks employedby the receiver 100 of FIG. 1. The receiver module 166 accepts thefeedback of this precoding matrix selection, and the decoder module 167provides them to the pre-coder module 157.

Once the R spatial stream(s) are generated from the MCS module 156, aprecoding matrix is applied to generate P≧R output streams. Note that Pis equal to R only if R>1 since P>1 and R≧1. The precoding matrix PM isselected by precoder module 157 from a finite pre-determined set ofpossible linear transformations or matrices, defined as the precodingmatrix codebook, which corresponds to the set that is used by thereceiver 100 of FIG. 1. Using pre-coding, the R spatial stream(s) arecross-combined linearly into P output data streams. For example, ifthere are 16 matrices in the precoding codebook, a precoding matrixindex (PMI) corresponding to the index to one of the 16 matrices in thecodebook for the subband (say 5, for example) is signaled from thereceiver 100 by sending from UE of FIG. 1 to the eNB for use bytransmitter 150 of FIG. 2 for the subband. The precoding matrix indexPMI then tells the transmitter 150 which of the 16 precoding matrices touse.

FIG. 3 illustrates five subbands of five frequency-domain resourceblocks wherein a precoding matrix selection provides a single precodingmatrix for each subband, as shown. Compare FIG. 9. In the context of the3GPP E-UTRA, each of the resource blocks represents 180 kHz of bandwidth(each RB consisting of 12 OFDM/OFDMA sub-carriers) thereby giving a 5-RBsubband size of 900 kHz for each of five CQI-related reports and fiveprecoding matrices selected respectively for the five sub-bands. Thisgrouping provides a practical subband size for many applications.

As discussed in connection with FIGS. 3-4, the precoding matrixselection corresponds to a grouping of frequency-domain resource blocksRBs employed by the receiver 100 of FIG. 1. A subband of the operatingbandwidth corresponds to a collection of one or more RBs. One sub-bandis defined as the smallest unit for precoding matrix selection andreporting of precoding matrix and CQI. That is, the RBs are concatenatedor grouped, thereby reducing the precoding matrix reporting overhead andthe control channel overhead in the downlink that signals theirallocated RBs to UEs that have been scheduled. The precoding matrixselection provides a single precoding matrix for each subband.

Actual selection of the precoding matrices depends on an optimalitycriterion, such as one related to channel quality indicator CQI, such asthe sum throughput that a subband provides, mutual information, or worstcase throughput or a specified maximum error rate for the subband orsome other now-known or future optimality criterion.

In FIG. 4, the grouping of the resource blocks RBs into subbands isvariable or fixed depending on a level of signaling support available.For example, the grouping varies depending on the channel qualityafforded by the resource blocks involved. Or, the grouping is fixed ifthe channel quality indicator CQI is high for the resource blocksinvolved. In one example, the subband size (the number L_(j) of resourceblocks within each subband j in FIG. 4) is fixed only throughout theentire communication session, or within each data frame. For fastervariation, the downlink control channel is used to communicate thechange in the grouping scheme. Slower variation can benefit from thedownlink broadcast (common control) channel, which is transmitted lessfrequently, or higher layer signaling.

In general, the grouping scheme or the subband size used in UE in FIG. 1is configurable by the network and/or the transmitter (base station ofFIG. 2). It is also, possible, however, for the FIG. 1 receiver 100(user equipment UE) to request the FIG. 2 transmitter 150 and/or thenetwork to change the grouping scheme/size. This request is suitablyconveyed via a low-rate feedback (e.g., sparse physical layer feedbackor higher layer feedback signaling). This is relevant when the downlinkinterference characteristic is highly frequency selective.

FIG. 5 shows a hypothetical CQI variation in the frequency domain.Average CQI in each subband approximates the CQI for each RB in thesubband.

FIG. 6 shows a vector average CQI₁, CQI₂, . . . CQI₃, . . . CQI_(M) forsubbands SB₁, SB₂, . . . , SB_(j), . . . SB_(M) respectively. Theaverage CQI_(r,j) indexed by each subband j and codeword r is reportedeither directly or in compressed form as discussed in detail elsewhereherein. (In the subscripting, a comma is sometimes used as a separatorfor clarity, and if no comma is present different lettered indices arestill regarded as independent.) For compactness of notation a vectorS_(rj) is used interchangeably to represent CQI_(r,j). In FIG. 6, forspatial codeword r in a hypothetical numerical example, CQI_(r,1)=3,meaning that the channel quality indicator for the codeword r in subband1 has a CQI value of 3. Analogously, CQI_(r,2)=4, etc. and CQI_(r,M)=1.

In FIG. 7, UE operation commences at a BEGIN 2105 and proceeds to selecta hybrid CQI feedback configuration mode at a decision step 2110 whichmonitors configuration transmissions of FIG. 8 from eNB. In one exampleof UE logic for decision step 2110 in FIG. 7, a mode called UEConfiguration Mode here is selected and operations go to a step 2114 toactivate UE Configuration Mode unless base station eNB in FIG. 8mandates otherwise. If base station eNB in FIG. 8 mandates otherwise asmonitored in step 2110, then operations instead select a mode called eNBConfiguration Mode here and branch to a step 2118 that activates the eNBConfiguration Mode.

These modes, UE Configuration Mode and eNB Configuration Mode,respectively establish parameters and controls over hybrid CQI feedbackthat are responsive to UE itself or base station eNB depending on theapplicable mode. The parameters and controls also define a scanningpattern or sequential feedback order in some embodiments, see e.g. FIGS.32-37. For CQI feedback about all subbands, i.e. not Best-m feedback, astep 2128 establishes a configured CQI feedback mode configured byeither UE or eNB for such CQI feedback and goes to step 2165.

For various forms of Best-m CQI feedback, i.e. involving selected andunselected subbands, the parameters and controls are established in someembodiments according to step 2122 for CQI Relative Mode or CQI AbsoluteMode or CQI Directed Mode, step 2124 for a number m of selectedsubbands, step 2126 specifying total number M of subbands and a widthgranularity number L for m selected subbands, and a step 2128 specifyinga Feedback Process Code for Best-m. Flow arrows couple each of steps2114 and 2118 to each of steps 2122, 2124, 2126, 2128 so that theapplicable UE Configuration Mode or eNB Configuration Mode establishesparameters and mode controls over hybrid CQI feedback.

If step 2122 establishes CQI Absolute mode, operations go to a loophaving steps 2130, 2135, 2138. In FIG. 7, loop 2130, 2135, 2138 selectsall CQI(j) such as SINR(j) in subband j that exceeds a predeterminedthreshold and such selection operationalizes the CQI Absolute mode. Notethat SINR is an exemplary definition of CQI, whereas CQI can also bealternatively defined as the index to the highest supportable modulationand coding scheme, index to the highest supportable code rate, forinstance. The loop uses the parameters M and L that were established instep 2126 to search all M subbands using width L. Step 2130 detectswhether the threshold is exceeded by the SINR in a given sub-band j. IfYes in step 2130, then operations proceed to step 2135 to record a one(1) at a position j (current value of index j) in a subband vector SV(j)and then go to step 2138 to increment the index j and/or codeword indexr. If No in step 2130, then operations instead record a zero (0) atposition j in SV(j) and proceed to step 2138 to increment the index j.If incremented index j exceeds the number M of subbands, the loop isDone and operations proceed from step 2130 to a step 2145.

If step 2122 establishes CQI Relative mode, operations go to a step 2140that selects a number m of subbands j of width L having, e.g., highestCQI (such as SINR, index to the highest supportable modulation andcoding scheme, index to the highest supportable code rate), and suchselection operationalizes the CQI Relative mode. Step 2140 uses theparameter m established in step 2124 and the parameters M and L thatwere established in step 2126, and searches all M subbands according tothe number M established in step 2126. Operations proceed from step 2140to step 2145.

If step 2122 establishes a CQI Directed mode under eNB ConfigurationMode, operations go to step 2145 and directly load a subband vectorSV(j) or SV(r,j) with a particular series of ones and zeros responsiveto, and/or as directed and/or specified by base station eNB step 2310 or2340 of FIG. 8. If step 2122 establishes a CQI Directed mode under UEConfiguration Mode, operations go to step 2145 and directly load asubband vector SV2 with a particular series of ones and zeros asdirected and/or specified by UE itself. In this way, particularsubband(s) can be selected for UE to report respective CQI values forthe subband(s).

At step 2145, a subband vector SV(j) or SV(r,j) is now constituted andhas M elements forming a series of ones and zeros that represent whethereach subband is selected or not. Next, a step 2150 counts the number ofones in subband vector SV to establish the resulting number m or m(r) ofselected subbands resulting when the CQI Absolute Mode has beenexecuted.

Note that defining the subband vector (SV) as a 1×M vector containing 1sand 0s is one exemplary method to indicate the position of the selectedsubbands. Alternatively, the position of the selected subbands isreported using compressed label or codebook index (e.g., bits jointquantized into fewer bits by UE codebook lookup using for examplelog₂(C_(M) ^(m)) bits, where C_(M) ^(m) denotes number of combinationsof M elements taken m at a time, m being the number of selectedsubbands).

A further step 2155 generates one or more CQI values (k₁ in number) forthe number nm of selected subbands due to either CQI Relative or CQIAbsolute mode. A step 2160 generates one or more CQI values (k₂ innumber) to either individually or collectively describe the un-selectedsubbands that are M−m in number. A total number k=k₁+k₂ of CQI value(s)are generated to describe the M subbands, where 1<=k<=M. (M is number ofsubbands.) The CQI value(s) generated in step 2160 for the un-selectedsubbands have a precision or accuracy that is less than the precision oraccuracy of the CQI values for the number m of selected subbandsgenerated in step 2155. This feature efficiently reduces the bits neededto communicate the CQI values for all M subbands as a whole.

Operations go from Best-m last step 2160 to a succeeding step 2165. ForCQI feedback other than Best-m, operations go directly from step 2128 tostep 2165 and bypass steps 2122 and 2130-2160.

Step 2165 assembles the CQI values into a CQI vector, to which isassociated a Feedback Process Code from step 2128, a scanning codeidentifying a scanning pattern (e.g., from FIG. 32-37), mode specifiersfrom step 2122, an identification UE_ID of the UE, CQI, rank and anyother relevant configuration information or representing-information notalready communicated by UE in some other way or already stored at basestation eNB. Then depending on the Feedback Process Code, a decisionstep 2170 flows operations sequenced according to the scanning code toany one (or more) of several CQI feedback processes for rank R>=1described elsewhere herein, such as Down Sample 2175, Predistortion2180, Frequency Differential 2185, Transform/Wavelet 2190, Mean andDelta 2195 and/or Parameterized 2198. Various embodiments of process andstructure remarkably alter and modify these feedback processes intoforms especially adapted for efficient MIMO CQI feedback involvingsubbands across code words for rank R>=2, as further described elsewhereherein. The CQI feedback output is transmitted from each UE to basestation eNB on uplink UL. The transmission itself can represent aservice request, or an explicit service request code can be included inthe transmission.

In FIG. 8, base station eNB begins configuration in a step 2305, selectsa CQI feedback configuration mode in a step 2310 and configures orallocates subsets of subbands for each UEi and establishes scanningcodes in a step 2320. Base station eNB requests a CQI report from eachUEi either in a CQI feedback mode and scanning pattern selected by UEwith permission from eNB in a step 2330 or according to a CQI feedbackprocess and scanning pattern that is initiated in a step 2340 by eNB. InBest-m CQI feedback, the amount of feedback is reduced because each UEionly reports CQI for the pertinent subbands identified or implied by theconfiguration established. Moreover, each UEi in some embodiments savesprocessing power and time by restricting channel estimations and channelquality determinations to those subbands and/or RBs configured for UEiby the eNB.

Computational burden or complexity of full encoding/decoding(compressing/decompressing) of CQI is acceptable and for some processeseven entails only logic operations, numerical additions and shifts. Thecomputational complexity increase is marginal compared to the benefitachieved from reducing the feedback overhead in the communicationschannel. With many UEs in a wireless communications system sendingfeedback to a base station, it is desirable to avoid any unnecessarycongestion and instead provide intelligent and smartly compressed CQIfeedback from each UE. Compressed CQI information is suitably sent inthe uplink control channel in the form of control information, or senttogether with uplink data in a physical uplink shared channel. CQI isone of or a combination of various feedback quantities such as (but notlimited to) the signal-to-interference plus noise ratio (SINR), spectralefficiency, preferred data rate and modulation-coding scheme MCS,capacity-based or mutual information, and/or received signal power.

In FIG. 8, Node B at step 2350 applies the CQI feedback from the UEsaccording to the configured scanning pattern(s) and recovers orreconstructs the CQIs originally determined by each UEi. Base stationeNB scheduler 2360 allocates or configures subband(s) customized foreach applicable UEi such as to perform user selection of which UE toschedule on a given transmission bandwidth at a given time, see alsoFIG. 9. Further, for the selected UE, the node B determines atransmission rank, a coding scheme for different layers and a modulationscheme for each layer. Node B step 2370 establishes precoding matrix PMand transmits to the UEs using MIMO in a manner determined by thescheduler, whence a RETURN 2390 is reached.

In UE joint quantization, a codebook of all valid feedback differencevectors is chosen. One example of a codebook has a well-chosen set ofvectors which approximate actual difference vectors D with highprobability. Another example codebook has zero-sum sequences withoptimized inter-element Euclidean distances established or revised byusing, for example, the Lloyd algorithm.

Quantization of the CQIs can involve an absolute value of at least oneCQI or an average CQI of the selected sub-bands. Averaging is performedbased on any suitable function (e.g., arithmetic mean, geometric mean orexponential averaging) selected for the purpose. A differential value ofthe CQI with respect to a reference value is suitably included in thefeedback either directly or in joint quantized form. The reference valueis determined employing the CQIs of selected sub-bands or using allsub-bands. For example, an average CQI of all sub-bands, an average CQIof the selected sub-bands or the CQI of neighboring sub-bands are somesuitable alternatives. Optionally, a single average CQI for unselectedsub-bands is employed. Alternatively, this average CQI is calculated forall the sub-bands unless the average CQI across all sub-bands is used asa reference value. Other CQI compression schemes employed on the CQIs ofthe unselected sub-bands are applied in still other embodiments.

MIMO spatially differential CQI compression is used for feedback to abase station. Frequency-domain compression processes herein are suitablyapplied to one transmission stream's CQI. Then, the difference betweenthe chosen stream's CQI and the other stream's CQI is computed on eachsub-band, or on a configured set of subbands (e.g., wideband/mediam/meanCQI), or on a selected set of subbands (e.g., Best-m subbands). Thedifference CQI (also known as differential CQI) is then compressed usingthe techniques discussed.

Spatial differential CQI corresponding to the mean or center sub-banduses fewer bits than the first-stream CQI. Spatial differential CQI forthe other sub-bands (frequency-domain differential or non-centersub-bands) can also realize some reduction in bits. Hence, it is alsopossible to apply the spatial differential only to the center sub-bandor the wideband (e.g., mean) CQI across sub-bands.

The CQI difference is computed between the streams before compression.Alternatively, the base stream is first compressed and quantized and thedifference of the other stream's CQI with respect to this quantizedoutput is selected for further compression and quantization.

MIMO joint difference coding CQI compression is used for feed back to abase station as an extension of the mean and differential CQIcompression approach. Here, the mean is computed across all sub-bands ora configured set of subbands and all streams. Then, for each (stream,sub-band) the difference with respect to the mean is fed back. Thismethod is based on the spatial variation and the variation acrossfrequencies both being small compared to the wideband CQI (e.g., mean),which is determined by the geometry of the UE.

Additionally, the compressed CQI feedback in some embodiments alsoincludes corresponding positions of the selected sub-bands, such assub-bands having best CQI.

The compressed CQI in some embodiments corresponds to a wavelet-basedCQI that provides a wavelet based on orthogonalizing a basis vector fora mean and differential CQI. In other words, the compressed CQI isgenerated by a transform that multiplies by two or more (e.g.,orthogonal) basis vectors to generate two or more transform coefficientsfor UE to feed back to Node B. The transform is suitably appliedaccording to various alternatives: 1) multiply-accumulate across the CQIvector of FIG. 5, one codeword at a time, 2) multiply-accumulatespatially across code words, one subband at a time, 3) performtwo-dimensional transform, or 4) perform other suitable transform.

In some other embodiments, the compressed CQI corresponds to ahierarchical granularity refinement CQI that provides difference-basedwavelet coefficients chosen in time for a recursively divided set ofsub-bands.

In one embodiment, the compressed CQI corresponds to a codebook indexfrom a codebook with entries including a plurality of CQI vectors ofabsolute CQI values across sub-bands (CQI profiles). Or, the compressedCQI corresponds to an index for a codebook element that is closest to anactual differential CQI vector. In that case, the codebook elementsapproximate differential CQI vectors to which actually-generateddifferential CQI vectors are compared to select the index as compressedoutput (joint quantized) for feedback from UE to eNB. Alternatively, thecompressed CQI corresponds to a basis function representing at least onesub-band CQI selected from a set of sub-band CQIs for the transmissionbandwidth.

For MIMO CQI feedback, the compressed CQI suitably corresponds to eachof a set of compressed CQIs for each sub-band that is determinedindependently for each of a plurality of spatial transmission streams.Or the compressed CQI instead corresponds to a spatially differentialCQI for each sub-band that is determined as a difference CQI between areferenced one of a plurality of spatial transmission streams and eachremaining one of the plurality of spatial transmission streams.Alternatively, the compressed CQI corresponds to a joint difference CQIfor each sub-band that is determined as a difference CQI between each ofa plurality of spatial transmission streams and a wideband CQI acrossthe plurality of spatial streams for a set of sub-bands.

In FIG. 9, in an orthogonal frequency division multiple access (OFDMA)communication system the total operating bandwidth is divided intonon-overlapping resource blocks (RB), and transmissions from userequipments (UEs) occur in an orthogonal, not mutually interfering,manner. Each RB can potentially carry data to a different UE, or each UEgets a well-chosen set of resources where it has a highsignal-to-interference and noise ratio (SINR) so that the spectralefficiency of the transmission is maximized according to the operatingprinciple of a scheduler.

To enable near-optimum frequency domain scheduling, each UE feeds backthe SINR or channel quality indicator (CQI) it experiences, potentiallyfor each RB or for a set of RBs, to its serving base station (Node B).Efficient CQI feedback or reporting embodiments herein beneficiallycompress the amount of overhead incurred. CQI information acrossmultiple RBs can be highly correlated, and some embodiments explicitlyestablish the precoding matrix PM to not only effectuate highcorrelation among RBs or subbands in the same codeword (spatialinformation stream) but also high correlation between corresponding RBsor subbands across codewords or spatial information streams. Suchchannel correlation is leveraged in specific methods and structuresherein to reduce the CQI feedback overhead in the uplink (UL)communication from UEs to their serving Node B (base station eNB).

In multiple-input, multiple-output (MIMO) OFDMA systems, multiplespatial layers, or codewords (CW), can be transmitted simultaneously inthe same frequency spectrum. CQI report for MIMO systems involvesfeeding back: 1) the optimal transmission rank, i.e., the number R ofspatial layers to be multiplexed, 2) the channel quality indicator (CQI)for each codeword across RBs or subbands, and 3) precoding matrix index(PMI) across RBs for precoding based closed-loop MIMO.

CQI quantization and feedback for MIMO-OFDMA systems is described inmore detail herein. Note that here CQI means the channel qualityindicator of each codeword, and is distinct from the precoding matrixindex PMI. Moreover, some embodiments herein now provide methods andstructure embodiments in PMI feedback, where sufficient analogy existsto permit their application to PMI.

Consider an OFDMA system with operating bandwidth divided into Nresource blocks (RBs). A resource block has a set of adjacentsub-carriers (tones). A 3GPP LTE system with 5 MHz bandwidth has N=25RBs, each of 180 kHz, for a total operating bandwidth of 4.5 MHz afterallowing the remaining 0.5 MHz bandwidth to be used for band edgeinterference protection. For scheduling purposes, the RBs areconcatenated into larger subbands thereby fundamentally reducing the CQIreporting overhead and the control channel overhead in the downlink thatsignals to the scheduled UEs their allocation. In FIG. 4, one sub-bandconsists of L RBs, where L is a positive integer. Let M sub-bands existwithin the system bandwidth. In some embodiments or configurations, allthe M sub-bands are composed of the same number L of RBs as in FIG. 3.In some other embodiments or configurations, different sub-bands j havedifferent numbers L(j) of RBs as in FIG. 4, such as when N is not amultiple of L. In a MIMO OFDMA system with a rank R>1, the number M ofsubbands j for each spatial codeword r in some embodiments isindependent of codeword index r=1, 2, . . . R. In some otherembodiments, the number M of subbands varies with codeword index r suchthat M=M(r) and number N of resource blocks RBs is expressed by

$N = {\sum\limits_{r = 1}^{R}\; {\sum\limits_{j = 4}^{M{(r)}}\; {{L\left( {j,r} \right)}.}}}$

The worst-case channel profile may result in insignificant CQI variationwithin M sub-bands. Note that operation across RBs is a special casewith L=1. Since the channel CQI profile of FIG. 5 may vary over time, itis also beneficial to configure the sub-band size (the parameter L)semi-statically either by the Node-B or the network. The Node-B cansignal the change in L to the UE via higher layer signaling or broadcastchannel. While it is beneficial to have multiple possibilities for L,the number of possibilities can also be kept small for simplicity andeconomy.

Based on the channel and interference/noise variance estimates, the UEcomputes signal-to-interference-noise ratio (SINR) for all thesub-carriers. From this quantity, the channel quality indicator (CQI)for each sub-band is suitably derived, which will be denoted as S₁₁,S₁₂, . . . S_(1M), S₂₁, S₂₂, . . . S_(2M), S_(R1), S_(R2), . . . S_(RM),where S_(rj) denotes the CQI of the r-th codeword on the j-th sub-band.Note that CQI can be defined as other performance metrics (e.g. mutualinformation, received signal strength). The number of codewords that aretransmitted simultaneously is the rank, denoted as R.

Some background on CQI feedback for wireless systems is found in U.S.Patent Application Publication 2008-0207135 “CQI Feedback for OFDMASystems” of Aug. 28, 2008, and corresponding U.S. patent applicationSer. No. 12/036,066 (TI-64201) filed Feb. 22, 2008, which are eachincorporated herein by reference. When each sub-band has only one CQIvalue to be fed back, CQI quantization is performed in the frequencydomain. Such single codeword channel quality indicator SCW-CQI feedbackhas a set of sub-bands SB, defined for CQI S_(j) related UE operations,which is semi-statically configured by higher layers.

FIG. 7 illustrates three types of CQI feedback processes, amongothers: 1) wideband feedback wherein a single wideband CQI is reportedby regarding the entire OFDMA bandwidth as one subband, 2) UE-selectedsub-band feedback, and 3) eNB configured sub-band feedback.

UE-selected sub-band CQI feedback involves self-configuration of thefeedback method by UE itself. Out of the total M sub-bands, UE selects msub-bands. The value of m can be configured by UE or eNB in casemultiple m values are allowable in a given network system. Variousalternative criteria are suitably applied in choosing the m sub-bands.For example, the m sub-bands are selected with the highest CQI value(s),or the m highest SINRs, or the m highest throughputs. Or a number ofsubbands are selected such that performance is within aperformance-target range exceeding a CQI threshold. UE computes two CQIvalues. CQI value 1 corresponds to the wideband CQI, and CQI value 2corresponds to a single CQI assuming transmission only over the mselected sub-bands. CQI value 1 is reported to eNB with high resolution,for example using 4 or 5-bits. CQI value 2 is encoded differentiallyrelative to CQI value 1 and is fed back with lower resolution usingfewer bits x, e.g., 2 or 3-bits, taking into account the fact thatdifferential CQI is likely in actual system operation to have a smallerdynamic range and thus utilizes fewer bits. The position of the selectedm sub-bands is reported by UE to eNB, with either a bitmap (e.g., M-bits1011010 indicating each subband in spectrum order by a subband vector SVcorresponding to a given bit position as selected (one) or not selected(zero)), or a compressed label or codebook index (e.g., bits jointquantized into fewer bits by UE codebook lookup using for examplelog₂(C_(M) ^(m)) bits, where C_(M) ^(m) denotes number of combinationsof M elements taken m at a time). When the number of sub-bands M issmall, using bitmap provides simpler encoding by UE and may result insomewhat higher acceptable feedback overhead. When the number ofsub-bands M is large, a compressed label or codebook index can be moreefficient in terms of UE feedback overhead. eNB recovers the bitmap,i.e. a subband vector SV, by using the compressed label or codebookindex to access a corresponding SV codebook at eNB.

In eNB configured CQI feedback, one wideband CQI is reported using ahigh CQI resolution (e.g., 4 or 5 bits). Each sub-band CQI in thesub-band CQI set S is encoded differentially relative to the widebandCQI, and fed back to eNB. Fewer bits (e.g., 2 or 3-bits) are suitablyused in differential CQI feedback, taking into account the smallerdynamic range of the differential CQI which is probable in actual systemoperation. Note that here differential quantization is performed infrequency domain. Note here that “sub-band set” refers to the set ofsub-bands configured by higher layers.

For MIMO-OFDMA systems, there are multiple codewords (layers, MCW).Spatially distinct MIMO information streams are likely to have acorrelation so that CQI feedback bandwidth savings are realized.

In FIG. 10, one process for MIMO-OFDMA CQI feedback performs separateCQI feedback on different spatial codewords, where CQI of each codewordis independently quantized and reported. In other words, the CQI of afirst MIMO channel and a CQI of a second spatially distinct MIMO channelare independently quantized and reported. Although all codewords use thesame single codeword (SCW)-CQI feedback process on each codeword(spatial information stream), some embodiments apply different SCW-CQIfeedback algorithms on different codewords.

In FIG. 11, another alternative applies differential CQI feedback in thespatial domain. First, the spatial difference (delta CQI(j,r)) betweenthe r-th codeword's CQI and a reference codeword's CQI is computed oneach sub-band j, where codeword index r=1, . . . R. Thereference-codeword's CQI and the delta-CQI are then representedindependently and reported to eNB. When the CQI in codeword 1 iscorrelated with CQI in codeword 2 pairwise on same subband index jacross spatial streams represented by codeword index r values, thedifferences provide further beneficial compression for MIMO. Thereference CQI is fed back with high CQI resolution (e.g., 4 or 5-bits),and the differential CQI is fed back with fewer bits (e.g., 2 or 3-bits)because of its smaller dynamic range.

Depending on the type of CQI, the differential CQI can be defined inseveral ways. For example, in a first way (1), if the CQI represents aquantized signal-to-noise ratio (SNR) orsignal-to-interference+noise-ratio (SINR), differential CQI is defined,for instance, in terms of the difference between the CQI of interestrelative to a reference CQI. The reference CQI is quantized andrepresented as a binary codeword. At the same time, the differential CQIis quantized and represented as a shorter binary codeword. Thedifference is taken before or after quantization.

Alternatively, in a second way (2), if the CQI represents some measureof (discrete) spectral efficiency (e.g. transport block size per RB,modulation and coding scheme, spectral efficiency), differential CQI isdefined in terms of the difference in the indexing between the CQI ofinterest and the index of the reference CQI. Here, the term “indexing”refers to the index of a particular CQI value in a CQI table (e.g. thedecimal equivalent of the binary codeword representation). Compared tothe difference in the CQI value itself, the difference in CQI indexingis more suited in this case since the spacing in the spectral efficiencytable need not be uniform.

Note that any codeword can serve as the reference codeword forperforming spatial differential feedback. Moreover, the referencecodeword is beneficially established as the codeword that minimizes thedynamic range of the differential CQI of other codewords. A smallerdynamic range in the spatial domain can lead to higher CQI feedbackreliability, or reduce the number of bits in reporting differential CQI.In addition, different codewords or sub-bands in some embodiments arechosen as reference codewords or sub-bands for the CQI feedbackpurposes.

Any combination, variation, or generalization of different processesherein is suitably applied in the CQI feedback for MIMO OFDMA. Thefollowing Figures and description detail various embodiments for MIMOCQI feedback in the context of wideband CQI feedback, UE-selected or eNBselected feedback modes. Note that the description of some embodimentsdiscusses two codewords R=2 without limitation since embodiments aresuitably also applied in systems with more than two codewords R>2.

In FIG. 12, independent wideband CQI feedback for different spatialcodewords feeds back a single wideband CQI for each of the codewords.The wideband CQI of each codeword has high CQI resolution (e.g., 4 or5-bits).

In FIG. 13, spatial differential feedback is used in wideband CQIfeedback. The wideband CQI designated CQI₁ of the first codeword CW1serves as the differential reference. CQI₂, the wideband CQI of thesecond codeword CW2, is encoded differentially and reported relative toCQI₁ for CW1. Fewer bits are suitably used in reporting differential CQI(e.g. 2 or 3 bits), where ΔCQI=ƒ_(diff)(CQI₂, CQI₁).

Note that the difference function ƒ_(diff)( ) is specified in differentembodiments and implemented any of a variety of ways. For example, giventwo multibit values a and b, the difference function suitably rounds offthe difference a minus b represented by ƒ_(diff)(a,b)=RND(a−b) RoundingRND is any appropriate rounding function such as one that rounds to thenearest value expressed in the fewer number of bits to be supported.Another form of difference function operates by using the values a and bas input values and performing a table lookup that outputs a table valueto which the input values are mapped by the contents of the table.Depending on the form in which the CQI is expressed (decibels dB, ratioof signal power/noise power, index to the supportable modulation andcoding schemes, index to the supportable spectral efficiency) thedifference function can be chosen based on an exponential differencelog[exp(a)−exp(b)] or an arithmetic difference a-b or some otherdifference mapping.

Three approaches for differential CQI report for MIMO-OFDMA system arecategorized here:

-   -   1) Frequency differential CQI report only: In this case,        differential CQI report is calculated only in the frequency        domain, where CQI report for different codewords is performed        independently. For each codeword, the subband CQI is encoded        differentially with respect to a reference CQI (e.g., the        medium/mean/wideband CQI of the same codeword). The reference        CQI is reported with high resolution (e.g., 4-5 bits) and the        subband differential CQI, which usually has a smaller dynamic        range than the reference CQI, is suitably reported with lower        resolution (e.g., 2-3 bits).    -   2) Spatial differential CQI report only: In this case,        differential CQI report is calculated in the spatial domain. For        instance, one codeword is selected as the reference codeword        wherein its reference CQI value is reported with high resolution        (e.g., 4 or 5 bits). Then CQI of the remaining spatial codewords        is encoded differentially with respect to the reference CQI of        the reference codeword and suitably reported with lower        resolution (e.g., 2-3 bits). Note that spatial differential CQI        can be computed for both subband CQI and/or wideband CQI, i.e.,        subband CQI is encoded differentially with respect to the        subband CQI of the reference codeword, and/or wideband CQI is        encoded differentially with respect to the wideband CQI of the        reference codeword (spatial delta).    -   3) Hybrid frequency differential and spatial differential CQI        report: a combination of the above two approaches is also        possible, where differential CQI calculation is performed in        both spatial and frequency domain. In this scheme, it is not        precluded that some CQI identities (e.g., subband CQI for each        codeword) are reported with frequency differential CQI report        (e.g., encoded differentially with respect to the wideband CQI        of the same codeword), and some other CQI identifies (e.g.,        wideband CQI of different codewords) are reported with spatial        differential CQI report (e.g., encoded differentially with        respect to the wideband CQI of a reference codeword).

In one form of SCW-CQI feedback, the wideband CQI is reported as thereference. CQI of each sub-band is encoded differentially with respectto the wideband CQI and reported to eNB. For MIMO CQI feedback withmultiple codewords, several process and structure embodiments areprovided here.

One category of embodiments for MIMO are entitled Spatial DifferentialCQI Reporting. In FIG. 14, each codeword computes its wideband CQI,where the wideband CQI of the r-th codeword is denoted by S_(r,wb). Eachwideband CQI is reported to eNB with high resolution (e.g., 4 or 5bits). Then for the j-th sub-band of the r-th codeword, CQI S_(rj) isencoded differentially with respect to the wideband CQI S_(r,wb). Thedifferential CQI ΔS_(rj)=ƒ_(diff)(S_(r,wb), S_(rj)), j=1, . . . M, andr=1, . . . R, is reported to eNB, preferably with fewer bits (e.g., 2 or3-bits).

It is believed that hitherto, CQI feedback methodology has responded tosystem constraints by applying the differential wideband CQI feedbackapproach of FIG. 13 as an alternative to subband-specific differentialCQI feedback of FIG. 14 or FIG. 11, for instance. The widebandalternative of FIG. 13 provides a limited amount of CQI feedback on itsown terms and thus gives an appearance of feedback bit-efficiency andsufficiency individually. Analogously, the alternative of FIG. 11 or 14provides a more granular amount of CQI feedback on its own terms andthus gives an appearance of wider feedback coverage sufficiencyindividually. However, such alternative-process methodologies eachinsufficiently respond to the need for CQI feedback that is both highlyefficient in terms of CQI feedback bits per subband per codeword andprovides more extensive CQI feedback coverage of subbands and codewords.

Some of the embodiments herein solve this problem by recognizing thatthese hitherto alternatively-treated CQI feedback processes should notbe treated as alternatives but instead as complementary parts of acomprehensive CQI reporting solution as taught herein. Accordingly,subband-specific CQI reporting in FIG. 15 delivers such a comprehensiveCQI reporting solution combining complementary parts whereinsubband-specific CQIs for a given codeword are encoded differentiallyrelative to the wideband CQI or other reference CQI (mean, median, etc.)for that codeword, and the wideband CQI (or other reference CQI) for allbut one of the codewords are encoded differentially relative to thewideband CQI (or other reference CQI) for the remaining codeword. Inthis way, both the bit-efficient feedback of differentially encodedwideband CQIs for the codewords and the bit-efficient feedback ofdifferentially encoded subband-specific CQIs for the codewordscomplement one another in the FIG. 15 embodiment and other analogousembodiments herein to provide both enhanced bit-efficiency and moreextensive CQI coverage of subbands and codewords for MIMO.

In FIG. 15, the wideband CQI of codeword 2 is encoded differentiallyrelative to the wideband CQI of codeword 1 (CW1). In this embodiment,instead of feeding back the absolute value of wideband CQI S_(2,wb), theprocess feeds back its spatial differentialΔS_(2,wb)=ƒ_(diff)(S_(2,wb),S_(1,wb)) relative to the first codeword'swideband CQI S_(1,wb). The all sub-band CQI of codeword 2 is reporteddifferentially, after generating it using S_(2,wb) itself as thereference. That frequency differential CQIΔS_(rj)=ƒ_(diff)(S_(r,wb),S_(rj)), j=1, . . . M, is reported to eNB,with fewer bits, and is one example of a differential subbands CQIvector that is generated for each codeword r=2, . . . R.

In FIG. 16, a process embodiment performs additional differentialreporting between the differential CQI sequences of each codeword. Forexample, denote the differential CQI sequence of codeword 1 CW1 as{ΔS₁₁, ΔS₁₂, . . . ΔS_(1M)}, differential CQI sequence of codeword 2 as{ΔS₂₁, ΔS₂₂, . . . ΔS_(2M)}. Instead of feeding back {ΔS₂₁, ΔS₂₂, . . .ΔS_(2M)}, the process feeds back ƒ_(diff)({ΔS₂₁, ΔS₂₂, . . . ΔS_(2M)},{ΔS₁₁, ΔS₁₂, . . . ΔS_(1M)}) or ƒ_(diff)(ΔS_(2,j), ΔS_(1,j)) where thesubtraction of vectors between codewords is performed element-wise bysubband j. This is one example of a spatial differential between afrequency differential subbands CQI vector and another frequencydifferential subbands CQI vector, wherein the differential between themis also called a Delta Delta herein.

Note that the definition of differential CQI can be the same ordifferent for different differential quantities. Also, the differencefunction ƒ_(diff)( ) for computing the differential of the differentialCQI in some embodiments can be specified differently than differencefunction ƒ_(diff)( ) for computing the differential CQIs for purposes ofthe subtraction of vectors. Note that “subtraction” refers to a suitablyspecified difference function for the element wise operation, and is notlimited to particular definition of subtraction.

In FIG. 16, remarkably, wideband CQI of CW2 is encoded differentially towideband CQI of CW1 and furthermore the frequency differential subbandsCQI vector for CW2 is encoded spatially differentially to the frequencydifferential subbands CQI vector of CW1. Note that here the differentialCQI sequence (in frequency domain) is computed over the sub-band CQI setS, e.g., that is semi-statically configured by higher layer to includeall the sub-bands, or only a sub-set of the sub-bands in the systembandwidth.

Delta Delta (ΔΔ) is likely to have desirably reduced dynamic rangecompared to ΔS_(r,j) when there is substantial positive correlationbetween ΔS_(1,j) and ΔS_(2,j), for instance. Reduced dynamic rangefacilitates effective compression. Favorable UE geometry, high widebandSINR for all codewords, and favorable precoding matrix PM at eNB eachcontribute to a high positive correlation between ΔS_(1,j) and ΔS_(2,j)(i.e., correlation between differential CQIs for different codewords r).Accordingly, some embodiments operate eNB so that precoding matrix PM ischecked or even optimized for delivery of favorable wideband SINR forall codewords. If favorable SINR is not achieved at a given MIMO rankR>1, then the rank R is decremented or otherwise reduced and precodingmatrix PM is recomputed until favorable SINR is achieved at a lower MIMOrank or until the rank is reduced to one, R=1.

In FIG. 17, Frequency Differential Reporting, e.g., for eNB-configuredor UE-configured CQI Reporting, performs quantization on each codewordindependently. For the r-th codeword, the process selects the k-thsub-band as the reference, shown in contrasting color for each codewordor stream in FIG. 17. (Also, as illustrated, that k-th reference subbandmay vary as a function k(r) from codeword to codeword.) A determinationof the reference subband for instance is that subband which has the CQIwhich most closely approximates the mean CQI or median CQI over allsubbands for codeword r. Further, the process generates the pairwisedifferences ΔS_(rj)=ƒ_(diff)(S_(rj), S_(rk)), j=1, . . . M, between allother sub-bands CQI S_(rj) in the frequency domain and the referencesub-band CQI S_(rk) for each codeword so that r=1 . . . R. The referenceCQI S_(rk) and its position k is quantized and reported as a quantizedCQI with high resolution (e.g. 4 or 5-bits for CQI S_(rk) and log₂ Mbits for the position k), where the differential subbands CQI vectorΔS_(rj)=ƒ_(diff)(S_(rj), S_(rk)) is quantized and reported to eNB usinglower resolution (e.g., 2 or 3-bits). Note that in some embodiments thedefinition of differential CQI is the same for different differentialquantities such that the specified definition is the same regardless ofsub-band index j and given codeword r, and in some other embodiments thespecified definition is different for one or more subbands j and/or oneor more codewords r.

In FIG. 18, the CQI S_(2,k) of the reference sub-band k of the second orhigher codeword (r=2) is also spatially differentially encoded relativeto the reference CQI S_(1k) of codeword 1. This differential encoding isexpressed by ΔS_(rk)=ƒ_(diff)(S_(rk), S_(1k)), r=2 . . . R. The processgenerates pairwise differences ΔS_(rj)=ƒ_(diff)(S_(rj), S_(rk)), j=1, .. . M, between all other sub-bands CQI S_(rj) in the frequency domainand the reference sub-band CQI S_(rk) for each codeword so that r=1 . .. R. The reference CQI S_(1k) and its position k is quantized andreported as a quantized CQI with high resolution (e.g. 4 or 5-bits forCQI S_(1k) and 2 or 3-bits for the differential encodingΔS_(rk)=ƒ_(diff)(S_(rk), S_(1k)), r=2 . . . R, and log₂ M bits for theposition k(r), r=1 . . . R), and further the differential subbands CQIvector ΔS_(rj)=ƒ_(diff)(S_(rj), S_(rk)) is quantized and reported to eNBusing lower resolution (e.g., 2 or 3-bits).

In FIG. 19, pairwise differences of the adjacent subbands for eachcodeword are generated by the CQI reporting process. The CQI S_(2k) ofthe reference sub-band k of the second or higher codeword (r=2) is alsodifferentially encoded relative to the reference CQI S_(1k) of codeword1. This differential encoding is expressed by ΔS_(rk)ƒ_(diff)(S_(rk),S_(1k)), r=2 . . . R and k(r) is the reference subband index ref of FIG.19. The process generates pairwise differences of the adjacent subbandsΔS_(rj)=ƒ_(diff)(S_(rj), S_(r,j−1)), j=2 . . . M, and r=1 . . . R. Thereference CQI S_(1k) and its position k is quantized and reported as aquantized CQI with high resolution (e.g. 4 or 5-bits for CQI S_(1k) and2 or 3-bits for the differential encoding ΔS_(rk)ƒ_(diff)(S_(rk),S_(1k)), r=2 . . . R, and log₂ M bits for the position k(r), r=1, . . .R), and further the differential subbands CQI vectorΔS_(rj)ƒ_(diff)(S_(1j), S_(1,j−1)) is quantized for the first codewordCW1 and reported to eNB using lower resolution (e.g., 2 or 3-bits). Adifferential encoding of the differential CQI(s) (Delta Delta) isquantized for the second codeword CW2, and any other codewords CW3, etc.The Delta Delta is given by ΔΔS_(rj)=ƒ_(diff)(ƒ_(diff)(S_(rj),S_(r,j−1)), =ƒ_(diff)(S_(rj), S_(r,j−1))) for j=2, . . . M, and r=2, . .. R. The Delta Delta is fed back for each higher codeword CW2, etc.,using lower resolution (e.g., 2 or 3-bits).

In FIG. 20, pairwise differences of the subbands relative to a referencefor each codeword are generated by the CQI reporting process. The CQIS_(2,k) of the reference sub-band k (or mean or median or wideband CQI)of the second or higher codeword (r=2) is also differentially encodedrelative to the reference CQI S_(1k) of codeword 1. This differentialencoding is expressed by ΔS_(rk)=ƒ_(diff)(S_(rk), S_(1k)), r=2 . . . Rand k(r) is the reference subband index ref of FIG. 20. The processgenerates pairwise differences of the subbands relative to the referenceΔS_(rj)=ƒ_(diff)(S_(rj), S_(rk)), j=1, . . . M, and r=1 . . . R. Thereference CQI S_(1k) and its position k is quantized and reported as aquantized CQI with high resolution (e.g. 4 or 5-bits for CQI S_(1k) and2 or 3-bits for the differential encoding ΔS_(rk)=ƒ_(diff)(S_(rk),S_(1k)), r=2 . . . R, and log₂ M bits for the position k(r), r=1, . . .R), and further the differential subbands CQI vectorΔS_(rj)=ƒ_(diff)(S_(1j), S_(1k)) is quantized for the first codeword CW1and reported to eNB using lower resolution (e.g., 2 or 3-bits). Adifferential encoding of the differential CQI(s) (Delta Delta) isquantized for the second codeword CW2, and any other codewords CW3, etc.The Delta Delta is represented by the expressionΔΔS_(rj)=ƒ_(diff)(ƒ_(diff)(S_(rj), S_(rk)), =ƒ_(diff)(S_(1j), S_(1k)))for j= . . . M, and r=2, . . . R. The Delta Delta is fed back for eachhigher codeword CW2, etc., using lower resolution (e.g., 2 or 3-bits).

In this section, several embodiments of UE-selected CQI reporting forMIMO-OFDMA systems are described wherein selected subbands areidentified.

In FIG. 21, a hypothetical illustration of 10 subbands for a codewordCW1 shows application of a criterion that selects subbands SB 2, 3, 7,10 and reports a CQI_(r,best−m) for those subbands collectively. Awideband CQI is reported for the unselected subbands SB 1, 4-6, 8-9collectively.

In FIG. 22, a hypothetical illustration of 10 subbands for a codewordCW1 shows application of a criterion that selects subbands SB 2, 3, 7,10 and reports a CQI_(r,j(SV(j)=1)) for those subbands individually. Awideband CQI is reported for the unselected subbands SB 1, 4-6, 8-9collectively.

In FIG. 23, a process for CQI reporting individually reports the CQI foreach subband or selected subband in order of its frequency or inaccordance with a configured scanning pattern, see, e.g., FIGS. 30-35.

In a category of embodiments called Joint Sub-band Selection ondifferent codewords, the same set of sub-bands is selected for CQIreporting each of the codewords. The A-suffixed FIGS. 24A-31A eachdepict Joint Sub-band Selection on different codewords for respectiveembodiments. Because different codewords select the same set ofsub-bands, a single indication of their position suffices for allcodewords. Selection of a sub-band is based on a performance metricdefined over all codewords, and the result of the selection isrepresented by SV(j)=1 if a given subband j is selected and otherwiseSV(j)=0. Alternatively, the location of the m selected subbands isjointly reported using compressed label using log₂(C_(M) ^(m)) bits.Some examples of different implementations for the performance metricare 1) maximizing the sum throughput, summed over all codewords, 2)maximizing the arithmetic/exponential average CQI over all codewords, 3)maximizing the mean CQI over all codewords, and 4) minimizing thedifference between CQIs of different codewords.

One category of embodiments involves Independent Sub-band Selection ondifferent codewords as in B-suffixed FIGS. 24B-31B. For each codeword,the process performs sub-band selection independently. For the r-thcodeword (r=1, . . . R), the m sub-bands are selected using a selectioncriterion. The selection criterion is suitably based on the optimizationof a given performance metric, for example, the maximum SINR, themaximum CQI, the maximum mutual information, or the minimization of adistance measure to a specific performance (SINR, capacity) constraint.Selection of a sub-band is based on the results of applying the givenperformance metric, and the selection is represented by SV(r, j)=1 if aparticular subband j is one of the selected subband(s) for codeword rand otherwise SV(r, j)=0. Alternatively, the location of the m selectedsubbands is jointly reported using compressed label using log₂(C_(M)^(m)) bits. The number m of selected m sub-bands is fixed,semi-statically configured or dynamically configured, depending onembodiment and any dynamically changing bandwidth requirements. Thenumber m of selected sub-bands m, is the same number for all codewordsfor simplicity, but some embodiments can vary the number m(r) to bedifferent for some or all codewords. Each different codeword rpotentially has different subband positions j of its selected sub-bands.Accordingly, the reporting process for each codeword feeds back theindication of the position of the associated selected sub-bandsrespectively, see subband vector SV(r,j) of FIG. 7 and FIG. 43.

After UE selects the set of sub-bands on each codeword, sub-band CQIreporting is performed according to any one or more of the followingembodiments. An embodiment designated Best-m Average is described asfollows. For the r-th codeword (r=1, 2 . . . R), two CQI values arecomputed. CQ_(r,wb) corresponds to the wideband/mean/medium CQI ofcodeword r and is reported to eNB with high resolution. CQI_(r,best−m)is measured or generated as CQI based on transmission only over the mselected sub-bands as a whole. Or CQI_(r,best−m) can be computed using acollective measure such as the arithmetic average, or the exponentialaverage, or the mean, or the maximum or minimum, of the CQIs of the mselected sub-bands of the r-th codeword. In terms of feeding backCQI_(r,best−m), either its absolute value can be reported as in FIG. 21or its frequency difference relative to the wideband CQI(ΔCQI_(r)=ƒ_(diff)(CQI_(r,best−m), CQI_(r,wb))) in Joint Sub-bandSelection FIG. 24A and Independent Sub-band Selection FIG. 24B can bereported. Note that the definition of differential CQI could be the sameor different for different differential quantities.

In the case of Independent Sub-Band Selection, the process for differentcodewords can choose different sub-bands, therefore an indication of thepositions SV(r,j) of the selected sub-bands is reported for eachcodeword, e.g., FIG. 24A, FIG. 7 and FIG. 43. On the other hand, when aprocess embodiment for different codewords chooses the same set ofsub-bands, then one vector indicating the positions SV(j) of theselected sub-bands is reported, e.g., in FIG. 24B, FIG. 7 and FIG. 43.

A type of Best-m Average embodiment also performs additional CQIquantization in spatial domain. As an example, the wideband CQI ofcodeword 2 CQI_(2,wb) is encoded differentially with respect to thewideband CQI of codeword 1 (CQI_(1,wb)), hence further reduces thereporting overhead. The CQI S_(2,wb) of the wideband CQI of the secondor higher codeword (r=2) is thus differentially encoded relative to thewideband CQI S_(1,wb) of codeword 1. This differential encoding isexpressed by ΔS_(r,wb)=ƒ_(diff)(S_(r,wb), S_(1,wb)), r=2 . . . R and wbis the wideband CQI of FIGS. 24A and 24B. Note that the definition ofdifferential CQI can be specified the same or different for differentdifferential quantities. Similarly, different codewords can performsub-bands selection independently and choose different sub-bands (e.g.FIG. 24B), or perform sub-bands selection jointly and choose the samesub-bands (e.g., FIG. 24A). In the Independent case, a respectiveindication SV(r,j) of the positions of the sub-bands selected isreported for each codeword by operations in FIG. 7. For the Joint caseone vector SV(j) indicating the best m sub-bands position is reportedcommon to all codewords by operations in FIG. 7.

In FIGS. 25A and 25B, a spatial differential encoding of the frequencydifferential CQI(s) (Delta Delta) is quantized for the second codewordCW2, and any other codewords CW3, etc. The Delta Delta is given byΔΔS_(r)=ƒ_(diff)(ƒ_(diff)(S_(r,best−m), S_(r,wb)),=ƒ_(diff)(S_(1,best−m), S_(1,wb))) for r=2, . . . R. The Delta Delta isfed back for each higher codeword CW2, etc., using lower resolution(e.g., 2 or 3-bits). The report includes wideband CQI S_(1,wb) (e.g.,4-5 bits) and differential encoding ƒ_(diff)(S_(1,best−m), S_(1,wb))(e.g., 2-3 bits) for CW1. Also reporting for each higher codeword hasdifferential encoding ΔS_(r,wb)=ƒ_(diff)(S_(r,wb), S_(1,wb)), r=2 . . .R using lower resolution (e.g., 2-3 bits), and Delta DeltaΔΔS_(r)=ƒ_(diff)(ƒ_(diff)(S_(r,best−m), S_(r,wb)),=ƒ_(diff)(S_(1,best−m), S_(1,wb))) for r=2 . . . R using lowerresolution (e.g., 2-3 bits). Joint Sub-band Selection in FIG. 25A orIndependent Sub-band Selection FIG. 25B can be reported. In theIndependent case, a respective indication SV(r,j) of the positions ofthe sub-bands selected is reported for each codeword by operations inFIG. 7, whereas for the Joint case only one indication SV(j) of thesub-bands position is reported common to all codewords by FIG. 7operations. Note that the definition of differential CQI is specifiedthe same or different for different differential quantities.

Another category of embodiments called Best-m Individual Reporting ofFIGS. 26A-28B, 30A/30B,31B differs from Best-m Average of FIGS. 24A-25B.In Best-m Individual Reporting, one CQI is fed back for each selectedsub-band as in FIG. 22, instead of feeding back a Best-m average CQI forall m selected sub-bands as in FIG. 21. In Best-m Individual Reporting,first, a wideband CQI is reported to eNB with high resolution. Then theprocess feeds back the individual CQI of each selected sub-band, eitherthe absolute value (actual value without differencing) or itsdifferential value relative to the wideband CQI. An indication of theposition of the m selected sub-bands is sent to eNB as well. Note thatthe definition of differential CQI is specified the same or differentfor different differential quantities. Similarly, different codewordscan perform sub-bands selection independently and choose differentsub-bands (e.g., B-suffixed FIGS. 26B-31B), or perform sub-bandsselection jointly and choose the same sub-bands (e.g., A-suffixed FIGS.26A-31A).

Best-m Individual Reporting of FIGS. 26A-26B feeds back individualdifferential CQIs designated ΔS_(r,j)=ƒ_(diff)(S_(r,j), S_(r,wb)), r=1 .. . R using lower resolution (e.g., 2-3 bits) for each selected subbandj in the Best-m set for each codeword CW1, CW2, etc. Reporting for theunselected subbands is less numerous and provided as widebandCQI_(r,wb), CQI_(r,wb), etc. at higher resolution (e.g., 4-5 bits) forunselected subbands for each codeword CW1, CW2, etc.

In FIGS. 27A and 27B, Best-m Individual embodiments also performadditional CQI quantization in spatial domain. Best-m IndividualReporting here feeds back individual differential CQIs designatedΔS_(r,j)=ƒ_(diff)(S_(r,j), S_(r,wb)), r=1 . . . R using lower resolution(e.g., 2-3 bits) for each selected subband j in the Best-m set for eachcodeword CW1, CW2, etc. Reporting for the unselected subbands is lessnumerous and provided for first codeword CW1 as wideband CQI_(r,wb), athigher resolution (e.g., 4-5 bits) for unselected subbands for codewordCW1. Wideband CQI_(r,wb) of unselected subbands for codewords r=2, . . .M is encoded spatially differentially with respect to the widebandCQI_(r,wb) of codeword CW1, and sent back using fewer bits (e.g., 2-3bits/codeword) and hence further reduces the feedback overhead. Thisdifferential encoding is expressed by ΔCQI_(r,wb)=ƒ_(diff)(CQI_(r,wb),CQI_(r,wb)), r=2 . . . R and wb is the wideband CQI of FIGS. 27A and27B. Note that the definition of differential CQI is specified the sameor different for different differential quantities. Similarly, differentcodewords can perform sub-bands selection independently and choosedifferent sub-bands (e.g. FIG. 27B), or perform sub-bands selectionjointly and choose the same sub-bands (e.g., FIG. 27A). In theIndependent case, a respective indication SV(r,j) of the positions ofthe sub-bands selected is reported for each codeword by operations inFIG. 7. For the Joint case only one indication SV(j) of the best nmsub-bands position is reported common to all codewords is reported foreach codeword by operations in FIG. 7.

In FIGS. 28A and 28B, Best-m Individual embodiments perform stillfurther additional CQI quantization in spatial domain. Best-m IndividualReporting here feeds back individual differential CQIs designatedΔCQI_(r,j)=ƒ_(diff)(CQI_(r,j), CQI_(r,wb)), for codeword CW1 using lowerresolution (e.g., 2-3 bits) for each selected subband j in the Best-mset for codeword CW1. For the higher codewords, however, Best-mIndividual Reporting here feeds back individual spatialcross-differential CQIs designated ΔCQI_(r,j)ƒ_(diff)(CQI_(r,j),CQI_(r,j)), using lower resolution (e.g., 2-3 bits) for each selectedsubband j in the Best-m set for each codeword CW2, etc. Reporting forthe unselected subbands is less numerous and provided for first codewordCW1 as wideband CQI_(r,wb), at higher resolution (e.g., 4-5 bits) forunselected subbands for codeword CW1. Wideband CQI_(r,wb) of unselectedsubbands for codewords r=2, . . . M is encoded differentially withrespect to the wideband CQI_(r,wb) of codeword CW1, and sent back usingfewer bits (e.g., 2-3 bits/codeword) and hence keeps the feedbackoverhead down. This differential encoding is expressed byΔCQI_(r,wb)=ƒ_(diff)(CQI_(r,wb), CQI_(r,wb)), r=2 . . . R and wb is thewideband CQI of FIGS. 28A and 28B.

In FIGS. 28A and 28B, Best-m Individual with Spatial DifferentialReporting embodiments perform spatial cross-differential CQI reportingin conjunction with Best-m individual reporting. The wideband CQI ofcodeword 2 is fed back differentially relative to the wideband CQI ofcodeword 1, reporting ΔCQI_(r,wb)=ƒ_(diff)(CQI_(r,wb), CQI_(r,wb)).Moreover, the individual CQI of the selected m sub-bands of codeword 2is encoded differentially with respect to the individual CQI of the msub-bands of codeword 1, i.e., individual spatial cross-differentialCQIs. Note that the definition of differential CQI is specified the sameor different for different differential quantities. Similarly, differentcodewords can perform sub-bands selection independently and choosedifferent sub-bands (e.g. FIG. 28B), or perform sub-bands selectionjointly and choose the same sub-bands (e.g., FIG. 28A). In theIndependent case, a respective indication SV(r,j) of the positions ofthe sub-bands selected is reported for each codeword by operations inFIG. 7. For the Joint case only one indication SV(j) of the best msub-bands position is reported common to all codewords is reported foreach codeword by operations in FIG. 7.

In FIGS. 31A and 31B, a differential encoding of the differential CQI(s)(Delta Delta) is quantized for the second codeword CW2, and any othercodewords CW3, etc. The Delta Delta is given byΔΔCQI_(r)=ƒ_(diff)(ƒ_(diff)(CQI_(r,j), CQI_(r,wb)), ƒ_(diff)(CQI_(r,j),CQI_(r,wb))) for r=2, . . . R. The Delta Delta is fed back for eachhigher codeword CW2, etc., using lower resolution (e.g., 2 or 3-bits).The report includes wideband CQI designated CQI_(r,wb) (e.g., 4-5 bits)and differential encoding ƒ_(diff)(CQI_(r,j), CQI_(r,wb)) (e.g., 2-3bits per Best-m subband) for CW1. Also reporting for each highercodeword has differential encoding ΔS_(r,wb)=ƒ_(diff)(S_(r,wb),S_(1,wb)), r=2 . . . R for unselected subbands using lower resolution(e.g., 2-3 bits). Further, the Delta Delta for selected subbands j isfed back as ΔΔCQI_(r)=ƒ_(diff)(ƒ_(diff)(CQI_(r,j), CQI_(r,wb)),ƒ_(diff)(CQI_(r,j), CQI_(r,wb))) for r=2, . . . R using lower resolution(e.g., 2-3 bits). Joint Sub-band Selection in FIG. 31A or IndependentSub-band Selection FIG. 31B can be reported. In the Independent case, arespective indication SV(r,j) of the positions of the sub-bands selectedis reported for each codeword by operations in FIG. 7. For the Jointcase only one indication SV(j) of the best nm sub-bands position isreported common to all codewords is reported for each codeword byoperations in FIG. 7. Note that the definition of differential CQI isspecified the same or different for different differential quantities.

Another category of embodiments performs spatial differential CQIquantization without frequency CQI quantization, where an example isgiven in FIGS. 29A-29B for UE-selected (best-m) average and FIGS.30A-30B for UE-selected (best-m) individual reporting.

FIGS. 29A-29B are examples of best-m UE-selected average CQI report withspatial differential quantization and without frequency-domainquantization. In brief, spatial differential reporting is performedbetween the wideband CQIs of different codewords, and between the best-maverage CQI (UE-selected) between different codewords, preferably usingfewer bits (e.g., 2-3 bits). In addition, the wideband CQI and best-maverage CQI (UE-selected) of the reference codeword is also fed backwith high resolution (e.g. 4-5 bits). For instance, consider aMIMO-OFDMA system with two spatial codewords. FIGS. 29A and 29B are eacha diagram of subbands in the frequency domain for different codewords,showing wideband CQI report for unselected subbands of the firstcodeword, wideband CQI report for unselected subbands of the secondcodeword encoded differentially with respect to the wideband CQI of thefirst codeword (spatial delta), best-m average CQI report for selectedsubbands of the first codeword, and best-m average CQI report forselected subbands of the second codeword encoded differentially withrespect to the best-m average CQI of the first codeword (spatial delta),and in FIG. 29A where the selected (best-m) subbands have the samesubband indices across codewords, and in FIG. 29B where the selected(best-m) subbands have different subband indices when compared acrosscodewords.

Note that in FIGS. 29A-29B no frequency differential CQI compression isperformed. However it is not precluded to perform additional frequencydifferential CQI compression, for example by reporting the best-maverage CQI of the selected subbands of the first codeword encodeddifferentially with respect to the wideband CQI of the first codeword.Similarly, such frequency differential CQI report can also be applied tothe remaining codeword (r=2, . . . R).

FIGS. 30A-30B are examples of best-m UE-selected individual CQI reportwith spatial differential quantization and without frequency-domainquantization. In brief, spatial differential reporting is performedbetween the wideband CQIs of different codewords, and between the best-mindividual CQI (UE-selected) for each of the selected subband betweendifferent codewords, preferably using fewer bits (e.g., 2-3 bits). Inaddition, the wideband CQI and best-m individual CQI (UE-selected) foreach of the selected subbands of the reference codeword is also fed backwith high resolution (e.g. 4-5 bits). For instance, consider aMIMO-OFDMA system with two spatial codewords, FIGS. 30A and 30B are eacha diagram of subbands in the frequency domain for different codewords,showing wideband CQI report for unselected subbands of the firstcodeword, wideband CQI report for unselected subbands of the secondcodeword encoded differentially with respect to the wideband CQI of thefirst codeword (spatial delta), Best-m individual CQI report for each ofthe selected subbands of the first codeword, and Best-m individual CQIreport for each of the selected subbands of the second codeword encodeddifferentially with respect to the Best-m individual CQI of thecorresponding subband of the first codeword (spatial delta), and in FIG.30A where the selected (Best-m) subbands have the same subband indicesacross codewords, and in FIG. 30B where the selected (Best-m) subbandshave different subband indices when compared across codewords.Additionally, it is not precluded to perform additional frequencydifferential CQI compression to the first codeword (i.e. the referencecodeword), by reporting the Best-m individual CQI of each of theselected subbands of the first codeword encoded differentially withrespect to the wideband CQI of the first codeword. Similarly, suchfrequency differential CQI report can also be applied to the remainingcodeword (r=2, . . . R).

Description now turns to FIGS. 32-37 for embodiments that includeScanning-based selective sub-band CQI Reporting herein. Having anefficient CQI reporting process addresses problems such as how to keepfeedback overhead low and simplify control signaling design in both theUEs and eNB, while maintaining and communicating accurate CQIinformation for downlink scheduling by eNB. Various embodiments asdescribed herein provide solutions. In orthogonal frequency divisionmultiple access (OFDMA) communication systems the total operatingbandwidth is divided into multiple resource blocks (RBs), as shown inFIG. 9, where transmissions from user equipments (UEs) occur in anorthogonal, not mutually interfering, manner. More typically, each UEwill get a well-chosen set of RBs, where it has a highsignal-to-interference and noise ratio (SINR) so that the spectralefficiency of the transmission is maximized according to the operatingprinciple of a scheduler. By scheduling each UE on RBs where it has highSINR, the data rate transmitted to each UE, and hence the overall systemthroughput, can be optimized according to the scheduling principle orpolicy employed.

In some embodiments, the system bandwidth is divided into severalsubbands, where each sub-band consists of n RBs. A scanning pattern isestablished and configuration data or instructions are provided in bothUE and eNB or provided in one of them (UE or eNB) and communicated tothe other (eNB or UE) prior to CQI feedback according to the scanningpattern. The CQI reporting according to the scanning pattern in someembodiments covers or communicates information about the entirebandwidth scanned. Using the scanning pattern, the UE selects one orseveral sub-bands at a given feedback instant. The CQI(s) correspondingto the selected sub-band(s) are reported to eNB. The process efficientlycompresses the CQI(s) at any feedback instant, and the selectedsub-bands are reported, resulting in a low overhead. CQI reportingcovers the entire system bandwidth, or such part of the system bandwidthas is specified or configured for CQI reporting according to thescanning pattern, after a certain time period during which the scanningprocess is operative. Where the entire system bandwidth is covered, eNBhas CQI information about the entire system bandwidth and can performscheduling more accurately. Uplink overhead is reduced because onlyscanned sub-bands report their CQIs. CQI accuracy and granularity isadaptively configurable by optimizing the scanning pattern.

For example, the scanning process scans the system bandwidth accordingto a scanning pattern, to select one or several sub-bands. Largefeedback overhead of systems lacking compression is substantiallyreduced. Substantial reduction of feedback overhead per sub-band makesengineering compromises unnecessary that only partially cover the systembandwidth in the CQI reporting, and instead allows the amount of CQIreporting to be increased so that the entire system bandwidth is coveredin the CQI report. CQI information is quantized and compressed, hencethe uplink feedback overhead is reduced. Uplink feedback and controlsignaling design is simplified due to the lower CQI feedback overhead,which consequently results in a better uplink feedback and controlchannel coverage. Some embodiments confer enhanced flexibility inadaptive configuration of the CQI feedback granularity, frequency, andoverhead, and enable easier and more fully acceptable trade-off offeedback overhead and throughput. UE executes the scanning process in afeedback generation module according to the scanning pattern. eNBreceives and interprets the report sent by the UE either according toeNB scanning configuration or by parsing the CQI report to determine thescanning pattern. eNB reconstructs the CQI of each subband for eachspatial codeword according to the scanning configuration. In this way, aset of scanning-based selected sub-band CQI reporting embodiments areprovided to efficiently feed back the CQI information over the entiresystem bandwidth. Uplink overhead is consequently decreased, uplinkcontrol signaling design is simplified and improved, uplink feedbackcoverage and control channel coverage are improved over subbands andcodewords and over time, and efficient performance and overheadtrade-offs are enabled.

To enable near-optimum frequency domain scheduling of UEs in the RBs ofthe operating bandwidth, each UE feeds back the SINR or channel qualityindicator (CQI) it experiences, potentially for each RB or forcombination of each RB, to its serving base station (Node B). EfficientCQI reporting embodiments herein beneficially compress the amount ofoverhead incurred and leverage the existence of substantial correlationof CQI feedback across multiple RBs.

In connection with FIGS. 32-37, 1, 2, 7, and 8, description hereinvolves scanning-based CQI reporting embodiments for systems such asOFDMA to address problems such as CQI feedback burden on systemscheduling and on speed in the network and CQI feedback-related latencyin UE and in eNB. Scanning-based CQI feedback embodiments describedherein help ameliorate and solve these problems by organizing,coordinating, parallelizing and/or pipelining the CQI feedbackprocessing as taught herein to obtain lower latency and higher systemspeed and relax constraints that might otherwise lead to poorcompromises in the communication system design. Scanning-based CQIreporting embodiments can have less reporting overhead than without anyCQI compression.

Using a configurable scanning pattern, parallelizing and pipelining ofthe CQI report processing are facilitated by making the index order ofoperations more uniform from block to block in UE and coordinated withthe index order of operations in eNB. The index order of operations iscalled a scanning pattern over subband/codeword indices (j, r). In thisway, various UE operations that can include CQI generation,differencing, writing (storing) and reading (loading), and transmissionof the CQI feedback in UEi are coordinated by using a same configurablescanning pattern. Correspondingly in eNB, the same scanning pattern isapplied in eNB uniformly for one or more of the various operationspertaining to UEi respectively. These eNB operations can include CQIreception, writing (storing) and reading (loading) of CQI feedbackinformation in decompression and decoding for low latency recovery ofUEi CQI(r,j)=S_(i,r,j) and to facilitate scheduling in eNB. For example,the eNB receives the encoded CQI feedback and on-the-fly de-differencesthat CQI feedback from a given UEi by the same scanning pattern in eNBas the sequential order by which that CQI feedback streams into eNB andsimilar or same as was used in the given UEi. Various embodiments aredescribed with different sub-band formations and scanning patterns. Thescanning-based CQI report embodiments are also described in the contextof multiple codewords (e.g. MIMO multi-antenna system).

Based on the channel and interference/noise variance estimates forsub-bands, the UE computes signal-to-interference-noise ratio (SINR) orother channel quality indicator (CQI) for each RB which is denoted asS1, S2, . . . , SN. Note that CQI in some embodiments uses otherperformance metrics such as the recommended transport format(modulation-and-coding scheme MCS), mutual information, and/or receivedsignal strength.

In one example of a scanning-based selective sub-band CQI reportembodiment, the entire bandwidth is divided into M sub-bands, each ofwhich is comprised of several adjacent or scattered RBs. The number L ofRBs in any sub-band varies between 1 and some maximum number Lmax.Different sub-bands can have different number of RBs. For a particularsub-band, in some embodiments its number of RBs can vary over time. Notethat the RBs in a particular sub-band are not necessarily adjacent toeach other. In other words, one sub-band is a set of scattered RBs.Comparing to FIG. 3, in one example, sub-band SB1 instead contains RBs1, 3, 5, 7, 8 for instance. In another scattered-RB example, SB1contains RBs 1, 6, 11, 16, 21.

Responding to the scanning-based CQI report from the UE, the Node Bperforms further processing by collecting the CQI reports over multiplesub-frames of FIG. 9. For instance, in one process embodiment the Node Bperforms link adaptation and scheduling in every sub-frame based on theCQI reports corresponding to the latest P sub-frames (where a completefrequency-domain CQI is obtained in P sub-frames). That is, the Node Breconstructs the frequency-domain CQI across the system bandwidth bycollecting the reports from multiple sub-frames. Some otherreconstruction techniques are used, e.g. interpolation, in some otherembodiments.

In the scanning-based CQI report, one or several sub-bands are chosenout of the total M sub-bands. CQIs of RBs in the selected sub-bands arethen fed back to the eNB. Selection of sub-bands is performed accordingto a specific scanning-pattern. In the following examples, severalscanning patterns for embodiments are described, assuming without lossof generality a 5 MHz system with 25 RBs, divided into 5 sub-bands.

In a Sequential Scanning pattern herein, each sub-band contains a set ofadjacent RBs. In sequential scanning, the k-th CQI feedback reports CQIof the j-th sub-band according to a pattern RB#, k+L(j−1) for which k 1,2, . . . L is repeated for each j=1, 2, . . . M according to a scanningprocess loop executed by processor or other circuit with the sequentialscanning pattern. Each subband contains a set of adjacent RBs. Forexample, and referring to FIG. 3:

Subframe 1: sub-band 1 is selected, with RBs 1-5 reported.

Subframe 2: sub-band 2 is selected, with RBs 6-10 reported.

Subframe 3: sub-band 3 is selected, with RBs 11-15 reported.

Subframe 4: sub-band 4 is selected, with RBs 16-20 reported.

Subframe 5: sub-band 5 is selected, with RBs 21-25 reported.

Some embodiments perform reporting according to a permuted version ofthe above pattern wherein UE sequentially feeds back sub-band N₁, N₂,N₃, N₄, N₅, where {N₁, N₂, N₃, N₄, N₅} is any arbitrary permutation,repetition, subset of the set {1, 2, 3, 4, 5}.

In Down-Sampled Scanning herein, The UE feeds back quantized versions ofevery L-th CQI. In down-sampled CQI reporting, a sub-band is composed ofa set of distributed RBs, e.g. every fifth RB in the example below, anddownsampling of the frequency spectrum has a specified offset k that isincremented to feedback RB#=L(j−1)+k, where j=1, 2, . . . M is repeatedfor each k=1, 2, . . . L by a process loop executed by processor orother circuit according to the down-sampled scanning pattern. Forexample, and referring to FIGS. 3-4:

Subframe 1: sub-band 1 is selected, with RBs 1, 6, 11, 16, 21 reported.

Subframe 2: sub-band 2 is selected, with RBs 2, 7, 12, 17, 22 reported.

Subframe 3: sub-band 3 is selected, with RBs 3, 8, 13, 18, 23 reported.

Subframe 4: sub-band 4 is selected, with RBs 4, 9, 14, 19, 24 reported.

Subframe 5: sub-band 5 is selected, with RBs 5, 10, 15, 20, 25 reported.

Here too, for some embodiments, the sub-bands indices {N₁, N₂, N₃, N₄,N₅} are any permutation, repetition or subset of the set {1, 2, 3, 4,5}.

In Dynamic Sub-band Selection herein, the sub-band selected at anyparticular time instant departs from a strict, static, or predeterminedpattern. A sub-band is fed back at any time, if necessary, for exampletriggered by a feedback command from either UE or eNB. In someembodiments, the Best-m CQI subbands are identified and scanned first inthe scanning pattern spatially across codewords in a given Best-msubband and then by a successive Best-m subband. In some otherembodiments, one sub-band can have a higher feedback frequency than theother sub-bands.

Any combination, subset, extension, and/or variation of the aboveembodiments are further embodiments. For example, Sequential Scanningand Down-Sampled Scanning are combined by performing down-samplingacross sub-bands. Using the above example of 25 RBs and assuming 12sub-bands (with each sub-band having 2 RBs except for the last one with3 RBs), see FIG. 4, the down-sampling is performed across sub-bands asfollows (transmission across 4 sub-frames):

Subframe 1: sub-bands 1, 5, 9 are fed back.

Subframe 2: sub-bands 2, 6, 10 are fed back.

Subframe 3: sub-bands 3, 7, 11 are fed back.

Subframe 4: sub-bands 4, 8, 12 are fed back.

Note that all the Figures and numerical values are exemplary and forillustrative purposes. Various embodiments generalize for any size ofsub-band, different number of RBs within the system bandwidth, differentRB sizes, etc.

In Dynamic Sub-band Formation, the RBs included in any sub-band aredynamically or adaptively configured over time, instead of choosing afixed set. For example, at a particular feedback instant, one sub-bandcontains RBs 1-5. At another feedback instant, in some embodiments, thissub-band contains another set of RBs, for example RB 1, 2, 7 9 10. Insome embodiments, configuration establishes at least one subband thatincludes two or more smaller-size sub-bands.

In multiple-input, multiple-output (MIMO) OFDMA systems, UEdetermines 1) the optimal transmission rank, i.e., the number of spatialstreams or codewords to be multiplexed and 2) the CQI for each stream oneach RB. The transmission rank R is assumed the same on all RBs, givingthe same number of CQIs to be fed back per RB. Some scanning-based CQIreporting embodiments for MIMO systems are described next.

In Spatially Independent Scanning-based Reporting herein, the CQIs fordifferent streams (spatial codewords) are independently fed back withthe scanning mechanism see FIG. 10 and any of FIGS. 32-37, for instance.The scanning patterns, number of sub-bands, number and indices of RBs ineach sub-band are different or identical, for different spatialcodewords.

In FIG. 11 for Spatially Differential Reporting herein, first, thedifference between the second stream's CQI and the first stream's CQI iscomputed on each RB or subband. The first-stream's CQI and the delta-CQIare quantized independently using the scanning-based mechanism and fedback according to a scanning pattern of any of FIGS. 32-37, forinstance.

In FIG. 14 for Joint Difference Coding herein, an extension of mean anddelta CQI method is applied. Here, the mean is computed across all RBs,or selected sub-bands, and all streams or a particular stream. Then, foreach (stream, sub-band) the difference with respect to the mean is fedback according to a scanning pattern of any of FIGS. 32-37, forinstance. This method is based on the spatial variation and thevariation across frequencies being both small compared to the mean,which is determined by the geometry of the UE.

Scanning-based CQI reporting for OFDMA can have a variety ofembodiments, some of which are non-exhaustively outlined in TABLE 1.

TABLE 1 SCANNING-BASED CQI REPORTING OUTLINE 1. For system with a singlecodeword (SISO, MISO, SIMO) a. Sequential scanning pattern b.Down-sampled scanning pattern c. Dynamic sub-band formation d. Anycombination or variation of the above schemes 2. For system (MIMO) withmultiple codewords a. Spatially independent scanning-based reporting b.Spatially differential reporting c. Joint difference encoding.

Further in FIGS. 32-37 for MIMO-OFDMA, CQI is a 2-dimensional matrix inboth frequency domain and space domain. With scanning-based CQIreporting, at each feedback instant, CQI of a particular space-frequencygrid is reported. The pattern according to which the space-frequencygrid is selected can be configured by eNB or UE, and is endowed with afixed configuration or is semi-statically or adaptively configured. Ascanning pattern is designed to cover the entire frequency-space domainfor feedback purposes over a specified period. Put another way, thescanning pattern covers the frequency-space domain by transmitting a CQIreport in more or less compressed form based on CQI of exhaustivenon-overlapping (mutually exclusive) proper subsets {CQI(SB_(j),CW_(r))} or averages over such subsets of the set of CQI having allindices j, r that encompass the frequency-space domain. Scanning-basedCQI reporting supports either single-codeword SCW CQI feedback(one-dimensional, 1-D) or multiple-codeword CQI feedback(two-dimensional, 2-D in the space-frequency domain) as taught herein.In the 2-D CQI feedback case, eNB/UE transforms the 2-D space-frequencyCQI into a 1-D CQI, and then the scanning patterns of FIGS. 32-37 areused.

In FIG. 32, Scanning feedback is performed first in the frequencydomain, and then in the spatial domain. At the beginning, the 1^(st)codeword is selected, and scanning feedback is performed in thefrequency-domain for this codeword. After codeword 1 has been scanned,codeword 2 is selected and its CQI is fed back according to a scanningfeedback pattern. In some embodiments different codewords use differentscanning feedback patterns in the frequency domain. FIG. 32 depicts twocodewords and five sub-bands j per codeword, and the number (1, 2, . . .10) denotes the feedback instant or sequential enumeration for which asub-band is scanned and reported. In another embodiment, frequencydifferential CQI report is applied, where for example CQI_(r,j) isdifferentially encoded with respect to a reference CQI (e.g. adjacentsubband CQI, or wideband/medium/mean CQI) of the r-th codeword. In yetanother embodiment, spatial differential CQI report is applied, wherefor example CQI_(r,j)(r=2, . . . R) is encoded differentially withrespect to CRI_(1,j) and reported using fewer bits (e.g., 2-3 bits).

In FIG. 33, Scanning feedback is performed first in the spatial domainr, and then in the frequency domain j. At the beginning, a sub-band j isselected, and scanning feedback is performed in the spatial-domain r tofeed back CQI(r=1, j), CQI(r=2,j). Then the next sub-band j+1 isselected according the scanning reporting pattern in the frequencydomain, and its spatial CQI vector CQI(r=1, j+1), CQI(r=2,j+1) isscanned and fed back, and so on. Some embodiments use a differentspatial-domain scanning reporting pattern, for different sub-bands j.FIG. 33 shows two codewords and five sub-bands, like FIG. 32, and thenumber (1, 2, . . . 10) enumerates each feedback instant or sequentialenumeration for which a sub-band is scanned, but in a different scanningpattern or scanning order in FIG. 33 than the order in FIG. 32.Similarly, it is not precluded to perform spatial/frequency differentialCQI quantization in addition to the scanning based reporting.

A static or semi-statically configured scanning embodiment of FIG. 32 orFIG. 33 is useful, for example, with the dynamic Best-m CQI reportingfor enhancing bit-efficiency of the feedback. Since the scanning patternis configured already, a flag bit is simply added to a CQI reportingvalue for a selected subband and omitted otherwise. Indeed, when thesame selected subbands for every codeword are established as the Best-msubbands as in A-suffixed FIGS. 25A-28A, such embodiment confersadditional CQI report bits-per-subband bit-efficiency. This is becausethe Best-m subband index j positions can be identified by inserting aflag bit the first time each position is used, and then the CQI reportfor the Best-m subbands for all the other codewords can be identified byparsing the CQI report according to the already-configured scanningpattern.

In FIG. 34, the scanning reporting process is a combination of thescanning reporting processes shown in, FIGS. 32 and 33. The scanningreporting pattern can be overwritten at any time, where the CQI of aspatial codeword at a sub-band is given more priority and scheduled tobe fed back prior to other subbands in the space-frequency grid. Forexample, suppose Best-m CQI reporting is configured for the best two(m=2) sub-bands of each codeword. CQI report data for these Best-msubbands are scanned out spatially in the dynamic scanning pattern 1, 2,3, 4 (numerals inside subband boxes of FIG. 34) prior to scanning outthe unselected subbands CQI. Notice that the enumeration of the scanningorder inside the subband boxes is distinct from the left-to-rightenumeration of subband index j values legended below the horizontalj-index axis of each of FIGS. 32-37. In FIG. 34, for codeword CW1, CQIsfor subbands j=1 and j=2 are the hypothetically-best ones (m=2), and arescanned first and third in the scanning pattern. For codeword CW2, CQIsfor subbands j=3 and j=5 are the hypothetically-best ones, and arescanned second and fourth in the scanning pattern.

In FIG. 35, the scanning feedback process handles codewords havingdifferent numbers of subbands j per codeword. Scanning reporting isperformed first in the frequency domain, and then in the spatial domain.At the beginning, the first codeword is selected, and scanning reportingpattern portion 1-5 is performed in the frequency-domain for thiscodeword. After codeword 1 has been scanned, codeword 2 is selected andits CQI is fed back according to a scanning reporting pattern portion6-9. In some embodiments, different scanning reporting patterns in thefrequency domain are applied for different codewords.

In FIG. 36, another scanning feedback process handles codewords not onlyhaving different numbers of subbands per codeword, but also varyingwidths of subbands varying with codeword index r. Codeword CW1 has foursubbands, and codeword CW2 as two subbands each twice as wide as any onesubband for CW1. Scanning reporting is performed first in the spatialdomain r, and then in the frequency domain j. At the beginning, asub-band j is selected, and scanning reporting is performed in thespatial-domain r to feed back CQI(r=1, j=1), CQI(r=2,j−1). Then the nextsub-band j+1 is selected according the scanning reporting pattern in thefrequency domain, and its spatial CQI vector CQI(r=1, j+1), CQI(r=2,j+1) is scanned and fed back. After the less numerous subbands for CW2are scanned, then the subbands 5 and 6 for CW1 are scanned. The order ofscanning feedback is 1, 2, 3, 4, 5, 6.

In FIG. 37, yet another scanning reporting process handles codewordshaving corresponding numbers M of subbands per codeword, but varyingwidths L of subbands j among the subbands for each codeword. Eachcodeword has four subbands, and one of the subbands (j=2, scanningelement 3) is wider than the other subbands for codeword CW1 and one ofthe subbands (j=2, scanning element 2) is wider than the other subbandsfor codeword CW2. Scanning reporting weaves cross-wise in the spatialdomain r, relative to the frequency domain j. The order of scanningreporting is 1, 2, 3, 4, 5, 6, 7, 8 as illustrated in FIG. 37.

Note that any of the various described scanning-based CQI reportingstructures and methods of FIGS. 32-37 and other scanning embodimentsdescribed herein are applicable to scanning-based CQI reporting of CQIs,differentially encoded CQIs (Deltas), differentially encoded CQIdifferences (Delta Deltas), codebook indices for joint quantization ofCQI, Deltas, and/or Delta Deltas, as described herein and/or as shown inany of the Figures herein, and further applicable to any combination ofany one, some or all of the foregoing.

Generalizing from FIGS. 32-37, a scanning pattern P_(i) herein for UEiis a mapping from a sequence of the counting numbers (e.g., s=1, 2, 3, .. . N, where N=RM) to a two-dimensional discrete index value space (r,j) for the subbands j of each codeword r, where 1≦r≦R and 0≦j≦M. (Indexj=0 is suitably used for CQI information pertaining to a CQI referencevalue for a given codeword. The subband index values 1≦j≦M are used toindex subband CQI values, CQI differences, and Delta Delta values bysubband.) UE reads out its computational storage, for instance, theCQIs, CQI differences, or Delta Delta values in any of the vectors ormatrices described herein according to the scan pattern configuredsuitably to the reporting process used in UEi. Conversely, eNB writesdirectly or indirectly to its computational storage, such as directly toprocessor registers for instance, the CQI differences and/or Delta Deltavalues and CQIs in any of the vectors or matrices described hereinaccording to the scan pattern configured suitably to the reportingprocess used in UEi. In some embodiments, the scanning process includesa scanning loop over a one-dimensional scanning pattern index (e.g.,s=1, 2, 3, . . . N, where N=RM) in the loop kernel has a mappingfunction from the one-dimensional scanning pattern index to generateindices r, j in a two-dimensional discrete index value space (r,j) forthe subbands j of each codeword r, where 1≦r≦R and 0≦j≦M. The loopkernel further includes a computation and/or read or write to storagethat involves variables as a function of the indices in two-dimensionaldiscrete index value space (r,j).

eNB performs computations to recover the CQI values S_(irj) insequential computational order as shown for eNB in each of theembodiments of FIGS. 38-42A. Accordingly, eNB very rapidly and withreduced latency recovers the CQI values S_(irj) in sequentialcomputational order when the scanning pattern P_(i), delivers CQI reportinformation from the UEi in a manner parallel to the sequentialcomputational order in eNB shown in any given one of those embodiments.In a first aspect, UEi and eNB use the same scanning pattern P_(i), sothat communication occurs intelligibly between them. In a second aspect,a scanning code is exchanged between UEi and eNB (or vice versa) thatidentifies a scanning pattern P_(i). Scanning pattern P_(i) identifiedby the scanning code confers high speed and low latency not only for UEsequential computational order used to generate CQI values S_(irj), anddifference and/or compress them, and transmit the difference/compressedform of CQI report from UE but also for eNB to recover the CQI valuesS_(irj) swiftly and with reduced latency in eNB. Scanning patterns maybe different for different UEi such as for different ranks. In someembodiments, eNB keeps a history of the scanning codes, and UEi savesbits by omitting the scanning code from the CQI report when the scanningcode is the same as the scanning code for the same scanning pattern usednext-previously.

For example, scanning order for reporting of pairwise differencesS_(r,j)−S_(r, j−1) for low UE and eNB latency suitably starts with thereference subband S_(r, REF) and then works backwards through thesubbands to subband j=1, and then works forward through the subbandsfrom the reference position to subband j=M. That way, step 3030 of FIG.39 is rapidly performed with low latency. A limited number of scanningpattern possibilities may exist for this reporting process, such as 1)working backwards and then forwards through subbands one codeword at atime, or 2) working forwards and backwards through subbands one codewordat a time, or 3) zig-zagging to progressively build backwards andforwards. On the other hand, in mean-Delta feedback, the scanningpattern for reporting of pairwise differences S_(r,j)−F_(r, 0) may havemore alternative pattern possibilities. Then the feedback process codeindicates Mean-Delta reporting, and a scanning code is provided tosignify which scanning pattern is being applied.

UE CQI computer 112 (FIG. 1) generates a CQI report derived from atleast a first and a second channel quality indicator (CQI) vectorassociated with a plurality of subbands for each of at least first andsecond spatial codewords respectively. UE feedback encoder/scanner 113is configurable by either of FIG. 7 steps 2114 and 2118 in response to ascanning code provided by either UE or eNB respectively. (An example ofthe scanning code is the last digit of the Figure number 32-37 hereinwhere those Figures illustrate various scanning patterns.) In FIG. 7,step 2165 includes the scanning code to send as a confirmation to eNB.UE feedback encoder/scanner 113 configurably establishes a scanningpattern for CQI reporting across the spatial codewords and subbands byreading them out as defined by the scanning pattern and initiatestransmission of a signal communicating the CQI report according to theconfigurably established scanning pattern.

UE CQI computer 112 generates a first and a second reference CQI for thefirst and second spatial codewords respectively. UE feedbackencoder/scanner 113 initiates transmission of information representingat least one of the first or second reference CQI at the beginning of orprior to executing the configurably established scanning pattern. In oneexample of Best-m feedback UE CQI computer 112 predetermines at leastone selected subband for each spatial codeword and the first referenceCQI includes a CQI for unselected subbands for the first codeword andthe second reference CQI includes a CQI for unselected subbands for thesecond codeword. UE feedback encoder/scanner 113 in some embodimentexecutes the configurably established scanning pattern for CQI reportingfor each selected subband prior to CQI reporting for unselectedsubbands. In this way the eNB scheduler has access to the CQI feedbackfor the selected subbands as soon as possible.

FIGS. 38-41, 41A, 42, 42A show process flow diagrams for embodiments ofUE and eNB. The flow diagrams approximately correspond to FIGS. 16, 19,20, 24/25, 24/25, 27/28, 27/28.

In FIG. 38, a process flow for Mean-Delta and Delta Delta CQI reportingcan be compared with FIG. 16. In the UE, a step 2510 quantizes the meanor median or wideband CQIs F_(0,r) across all subbands collectively foreach codeword r. Then a step 2515 generates wideband DeltasD_(0,r)=F_(0,r)−F_(0,1) for codeword index values r=2, . . . R. Next astep 2520 generates subband deltas D_(j,r)=S_(j,r)−F_(0,r) individuallyfor each of the subband index values j=1, 2, . . . M and for codewordindex values r=1, . . . R. A succeeding step 2525 generatesdifferentials of the differentials (Delta Deltas)ΔD_(j,r)=D_(j,r)−D_(j,1), for each of the subband index values j=1, 2, .. . M and codeword index values r=2, . . . R. In FIG. 38, a further step2530 sends uplink feedback 2540. Uplink feedback 2540 includes CQIfeedback vector (F_(0,1), D_(0,r), D_(j,1), D_(j,1), ΔD_(j,r), R)respectively representing wideband CQI for codeword CW1; wideband Deltasfor codeword index values r=2, . . . R; subband Deltas for codeword CW1;Delta Deltas for codeword index values r=2, . . . R; and the rank valueR. In FIG. 38, an alternative form of uplink feedback 2540 includes aCQI feedback vector (F_(0,1), D_(0,r), J₁, J_(r)). The elements of thisfeedback vector respectively represent wideband CQI for codeword CW1;wideband Deltas for codeword index values r=2, . . . R; joint quantizedvector subband Deltas D_(j,1) compressed and delivered by step 2530 as acodebook index J₁ for codeword CW1. Moreover, step 2535 compresses anddelivers the Delta Deltas delivered as R−1 respective codebook indicesJ_(r) determined by joint quantizing each of R−1 Delta Delta CQI vectorsover M subband index values j=1, 2, . . . M For the R−1 codeword indexvalues r=2, . . . R. The rank value R is implicit in the UE reporting.eNB counts the number of feedback indices J in the feedback or countsthe number of wideband deltas D_(0,r) therein plus one, or counts allthe feedback values and divides by two (by count shifting rightwardone), or executes some other suitable counting process. Alternatively,the rank value R is explicitly fed back to eNB.

In FIG. 38, for the base station eNB, operations commence with a BEGIN2601 and execute a decision step 2605 that determines whether anycodebook feedback is involved. In the meantime, feedback vectors areincoming to eNB from numerous UEs indexed i. If Yes at step 2605,operations proceed to a step 2610 and 2614 for codebook accesses. Step2610 uses codebook index J_(i1) (J₁ from UE i) to retrieve the subbanddeltas D_(j,1) for UEi for each of the subband index values j=1, 2, . .. M for codeword CW1. Step 2614 uses each of the R−1 codebook indicesJ_(i,r) (J_(r) from UE i) to codebook-retrieve the Delta Delta vectorΔD_(j,r) for UEi for each of the subband index values j=1, 2, . . . Mand R−1 codeword index values r=2, . . . R, whereupon a step 2618 isreached. In FIG. 38, eNB step 2618 is reached after step 2614 or in casecodebook feedback is not applicable at decision step 2605. Step 2618uses the Delta Deltas and the CW1 deltas and recovers the differentials(subband deltas) for each UEi and for all the codewords by a summingprocess expressed as D_(i,j,r)=ΔD_(i,j,r)+D_(i,j,1) for each of thesubband index values j=1, 2, . . . M and codeword index values r=2, . .. R. A succeeding step 2620 recovers the wideband CQIsF_(i,0,r)=D_(i,0,r)+F_(i,0,1) for codeword index values r=2, . . . R andall UEs i. Next a step 2625 recovers the original CQIs S_(i,j,r) for allUEs i by a process expressed as S_(i,j,r)=D_(i,j,r)+F_(i,0,r) for eachof the subband index values j=1, 2, . . . M and for codeword indexvalues r=1, . . . R. At this point the CQI information is recovered, andoperations proceed to the eNB scheduler 2630 to allocate subbands to UEsfollowed by a precoder that establishes precoding matrices for the UEsbased on the subband allocations. In a step 2640, the base station eNBtransmits over the downlink to the UEs using a composite precodingmatrix PM based on the precoding matrices thus established.

In FIG. 39, a process flow for Pairwise Delta and Delta Delta CQIreporting based on Pairwise-Delta of the adjacent subbands can becompared with FIG. 19. In the UE, a step 2810 quantizes CQI for areference subband F_(REF,r) for subband j-REF for each codeword r.Depending on embodiment, each reference position j=REF or j(r)=REF(r) isconfigured by eNB so that no reference position reporting need betransferred on the uplink. Alternatively, UE determines the referenceposition(s) and feeds them back on the uplink as well. Then a step 2815generates reference subband Deltas Δ_(REF,r)=F_(REF,r)−F_(REF,1) forcodeword index values r=2, . . . R. Next a step 2820 pairwise generatesM−1 adjacent subband differential vectors for the adjacent subbanddeltas Δ_(j,r)=S_(j,r)−S_(j−1,r), for each of the subband index valuesj=2, . . . M and for codeword index values r=1, . . . R. A succeedingstep 2825 generates differentials (Delta Deltas)ΔΔ_(j,r)=Δ_(j,r)−Δ_(j,1) for each of the M−1 adjacent subbanddifferentials for each of the codeword index values r=2, . . . R.

In FIG. 39, uplink feedback 2840 is sent from UE to eNB. Uplink feedback2840 includes CQI report vector (F_(REF,1), Δ_(REF,r), R, Δ_(j,1),ΔΔ_(j,r)) respectively representing reference subband CQI for codewordCW1; reference subband Deltas for codeword index values r=2, . . . R;the rank value R; adjacent subband Deltas for codeword CW1; and adjacentsubband Delta Deltas for codeword index values r=2, . . . R.

In FIG. 39, an alternative form of the uplink feedback includes a CQIreport vector (F_(REF,1), Δ_(REF,r), J₁, J_(r)) respectivelyrepresenting reference subband CQI for codeword CW1; reference subbandDeltas for codeword index values r=2, . . . R; joint quantized vectorsubband Deltas Δ_(j,1) delivered as a codebook index J₁ for codeword CW1from step 2830; and joint quantized Delta Deltas delivered as R−1respective codebook indices J_(r) from step 2835. The rank value R isimplicit, and eNB suitably counts the feedback values to obtain thevalue of rank R. Alternatively, the rank value R is implicitly reportedto the eNB. Some embodiments also joint quantize the reference subbanddeltas Δ_(REF,r) and send a single index J_(REF) in place of Δ_(REF,r).

In FIG. 39, for the base station eNB, operations commence with a BEGIN3001 and execute a decision step 3005 that determines whether anycodebook feedback from UE is involved. In the meantime, feedback vectorsare incoming from each UEi. If Yes at step 3005, operations proceed to astep 3010 and a step 3015 for codebook accesses. Step 3010 uses fed-backcodebook index J_(i1) (J₁ from UE i) to retrieve the adjacent subbanddeltas Δ_(j,1) for each of the subband index values j=2, . . . M forcodeword CW1. Step 3015 uses each of the R−1 codebook indices J_(i,r)(J_(r) from UE i) to codebook-retrieve the adjacent subbands Delta Deltavector ΔΔ_(i,j,r) for each UEi for subband index values j=2, . . . M andR−1 codeword index values r=2, . . . R, whereupon a step 3020 isreached.

In FIG. 39, eNB step 3020 is reached after step 3015 or directly fromstep 3005 in case codebook feedback is not applicable at decision step3005. Step 3020 recovers the reference subband CQIsF_(i,REF,r)=Δ_(i,REF,r)+F_(i,REF,1) for codeword index values r=2, . . .R and all UEs i. A succeeding step 3025 uses the Delta Deltas from step3015 and the CW1 deltas from step 3010 and recovers the differentials(adjacent-subband deltas) for each UEi and for all the codewords by asumming process expressed as Δ_(i,j,r)=ΔΔ_(i,j,r)+ΔΔ_(i,j,1) for each ofthe subband index values j=2, . . . M and codeword index values r=2, . .. R. Next a step 3030 first recovers the reference subband CQIs for eachcodeword r for the UEs i by a process that establishes reference subbandvalues S_(i,REF,r)=F_(i,REF,r). Then step 3030 reconstructs the originalsubband CQIs for subbands j>REF by the repeated additionS_(i,j,r)=S_(i,j+1,r)−Δ_(i,j,r) for codeword index values r=1, . . . R.Step 3030 goes on and reconstructs the original subband CQIs forsubbands j<REF by the repeated subtractionS_(i,j,r)=S_(i,j+1,r)−Δ_(i,j,r) for codeword index values r=1, . . . R.At this point the original subband CQI information is recovered, andoperations proceed to the eNB scheduler 2630 to allocate subbands to UEsfollowed by a precoder that establishes precoding matrices for the UEsbased on the subband allocations. In a step 2640, the base station eNBtransmits over the downlink to the UEs using a composite precodingmatrix PM based on the precoding matrices thus established.

In FIG. 40, a process flow for Reference Delta and Delta Delta CQIreporting can be compared with FIG. 20. In the UE, a step 3210configures the position of, and quantizes, a respective Referencesubband CQI F_(REF,r) for each codeword r. Then a step 3215 generatesReference Deltas (differentially encoded relative to reference subband)expressed as Δ_(REF,r)=F_(REF,r)−F_(REF,r) for codeword index valuesr=2, . . . R. Next a step 3220 generates Subband DeltasD_(j,r)=S_(j,r)−F_(REF,r) for each of the subband index values j=1, 2, .. . M and for codeword index values r=1, . . . R. Consequently, a zero(0) conveniently appears at the reference subband position in theSubband Delta vector. A succeeding step 3225 generates differentials ofthe differentials (Delta Deltas) ΔD_(j,r)−D_(j,r)−D_(j,1) for each ofthe subband index values j=1, . . . M and codeword index values r=2, . .. R. A further step 3230 sends uplink feedback 3240. Uplink feedback3240 includes CQI report vector (F_(REF,1), Δ_(REF,r), D_(j,1),ΔD_(j,r), R) respectively representing Reference subband CQI forcodeword CW1; Reference Deltas for codeword index values r=2, . . . R;Subband Deltas for codeword CW1; Delta Deltas for codeword index valuesr=2, . . . R; and the rank value R. Alternative reporting for FIG. 40uses joint quantized feedback Index J in some embodiments, analogous toFIG. 38.

In FIG. 40, for the base station eNB, operations at step 3305 receivesignals and unpack uplink feedback from UEs i. At a step 3310, theReference Deltas Δ_(REF,r), Subband Deltas D_(j,1) (CW1), and DeltaDelta vectors ΔD_(j,r) from each UEi are filtered to eliminate unusualoutlying values potentially due to noise error. A step 3315 recovers thereference subband CQIs F_(i,REF,r)=Δ_(i,REF,r)+F_(i,REF,1) for codewordindex values r=2, . . . R and all UEs i. A succeeding step 3320 uses theDelta Deltas and the CW1 Subband Deltas and recovers the Subband Deltasfor each UEi and for the codewords by a summing processD_(i,j,r)=ΔD_(i,j,r)+D_(i,j,1) for each of the subband index values j=1,2, . . . M and codeword index values r=2, . . . R. Next a step 3330 usesthe results of steps 3315 and 3320 and recovers the original CQIs forall UEs i by a process S_(i,j,r)=D_(i,j,r)+F_(i,REF,r) each of thesubband index values j=1, 2, . . . M and for codeword index values r=1,. . . R. At this point the CQI information is recovered, and operationsproceed to the eNB scheduler 2630 to allocate subbands to UEs followedby a precoder that establishes precoding matrices for the UEs based onthe subband allocations. In a step 2640, the base station eNB transmitsover the downlink to the UEs using a composite precoding matrix PM basedon the precoding matrices thus established.

In FIG. 41, a process flow for Best-m Average CQI reporting, with jointquantization and horizontal/vertical forms of the reporting, can becompared with FIG. 24A/B. In the UE, operations commence with UEconfiguration at a step 3605. The configuration type is found indecision step 3608 and can be established by UE or eNB. Then a step 3610configures the CQI reporting mode, and Best-m Average CQI reporting modeis illustrated. A succeeding step 3615 selects the best subbands as inFIG. 7 and reports their positions by setting corresponding bits ofsubband vector SV(j)=1. Alternatively, the selected subbands vector(SV), or the indication of the position of the m-selected subbands, canbe jointly reported using a compressed label with log₂(C_(M) ^(m)) bits.Unselected subbands have SV(j)=0. Next a step 3620 generates the mean ormedian or wideband CQI _(s)F_(r) for the selected subbands “s” for eachr-th codeword CW1, CW2, etc. Another step 3625 generates mean or medianor wideband CQI _(u)F_(r) for the unselected subbands “u” for each r-thcodeword CW1, CW2, etc.

In FIG. 41, differential encoding at a step 3630 generates deltas forthe selected subbands _(s)D_(r)=_(s)F_(r)−_(s)F₁ for each codeword CW2,etc., i.e. for index r=2, . . . R. Analogously, a step 3635 alsogenerates deltas for the unselected subbands _(u)Δ_(r)=_(u)F_(r)−_(u)F₁for each codeword CW2, etc., i.e. for index r=2, . . . R. Then a step3640 joint quantizes the delta _(s)D_(r) and outputs a codebook indexJ_(s). Step 3640 also joint quantizes the delta _(u)Δ_(r) and outputs acodebook index J_(u) as well, whereupon a UE RETURN 3655 is reached.

Uplink feedback 3670 is provided in any of a variety of embodimentsrelated to FIG. 41 and described next. In a first embodiment, a CQIreport vector is expressed as (SV, _(u)F₁, _(s)F₁, _(u)Δ_(r),_(s)D_(r)). In words, the CQI report vector has subband vector SV, theFIG. 21 mean/median/wideband collective CQI _(s)F₁ for the selectedsubbands for codeword CW1 and the FIG. 21 mean/median/widebandcollective CQI _(u)F₁ for the unselected subbands for codeword CW1. TheCQI report also includes the spatial CQI differences _(s)D_(r) betweencollective CQI _(s)F_(r) for the selected subbands relative to _(s)F₁for codeword CW1. The CQI report further has the spatial CQI differences_(u)Δ_(r) relative to CQI _(s)F₁ for the unselected subbands forcodeword CW1. This is called vertical CQI reporting herein because thespatial CQI differences can be listed in columns vertically in TABLE 2.When spatial CQIs are quite similar in magnitude across code words r,and vertical CQI reporting delivers compression because both the spatialCQI differences _(s)D_(r) and the spatial CQI differences _(u)Δ_(r) aresmall and easily represented with just a few bits.

TABLE 2 CQI REPORTING (“VERTICAL”) Unselected Selected Sub-bandsSub-bands CW1 _(u)F₁ _(s)F₁ CW2, etc. _(u)Δ_(r) _(s)D_(r)

In a second embodiment related to FIG. 41, a CQI report vector isexpressed as (SV, _(u)F₁, _(u)Δ_(r), _(su)D_(r)), see also TABLE 3. Inwords, the CQI report vector has subband vector SV, the FIG. 21mean/median/wideband collective CQI _(u)F₁ for the unselected subbandsfor codeword CW1. (_(s)F₁ need not be explicitly reported.) The CQIreport also includes the spatial CQI differences _(u)Δ_(r) relative toCQI _(u)F₁ for the unselected subbands for codeword CW1. Instead ofanalogous vertical report data _(s)D_(r) for the selected subbands, ahorizontal CQI report _(su)D_(r)=_(s)F_(r)−_(u)F_(r) delivers CQIdifferences in a given row for each codeword, r=1, 2, . . . R. Variantsof the second embodiment _(su)D′_(r)=_(s)F_((r+1)modR)−_(u)F_(r) foreach codeword, r=1, 2, . . . R, also can provide useful correlation in azig-zag or other scanning pattern for generating the spatial CQIdifferences. In other words, the scanning process teachings herein forFIGS. 32-37 are not only useful for generating the order of uplinktransmission of CQI report data but also useful for independently ordependently establishing pairs of values for differencing and/or theorder of transmission of difference-based CQI report data.

TABLE 3 BEST-m CQI REPORTING (“HORIZONTAL”) Unselected SelectedSub-bands Sub-bands CW1 _(u)F₁ _(su)D₁ CW2, etc. _(u)Δ_(r) _(su)D_(r)

In a third embodiment related to FIG. 41, a CQI report vector isexpressed as (SV, _(s)F₁, _(s)D_(r), −_(su)D_(r)), see also TABLE 4. Inwords, the CQI report vector has subband vector SV, the FIG. 21mean/median/wideband collective CQI _(s)F₁ for the selected subbands forcodeword CW1. (_(s)F₁ need not be explicitly reported.) The CQI reportalso includes the spatial CQI differences _(s)D_(r) for other spatialcodewords relative to CQI _(s)F₁ for the selected subbands for codewordCW1. A reverse-horizontal CQI report_(us)D_(r)=_(−su)D_(r)=_(u)F_(r)−_(s)F_(r) delivers CQI differences in agiven row for each codeword, r=1, 2, . . . R.

TABLE 4 BEST-m CQI REPORTING (“REVERSE-HORIZONTAL”) Unselected SelectedSub-bands Sub-bands CW1 −_(su)D₁ _(s)F₁ CW2, etc. −_(su)D_(r) _(s)D_(r)

In a fourth embodiment category related to FIG. 41, any of the firstthree embodiments are subjected to joint quantization in step 3640. TheCQI report vector has the form (SV, _(u)F₁, _(s)F₁, J_(u), J_(s), R) forvertical reporting, and the form (SV, _(u)F₁, J_(s), J_(us), R) or (SV,_(s)F₁, J_(s), J_(us), R) for horizontal reporting. In the latter case,J_(su) signifies a codebook index resulting from joint quantization ofthe horizontal difference vector _(su)D_(r). Alternatively, J_(us)signifies a codebook index resulting from joint quantization of thehorizontal difference vector −_(su)D_(r). For substantially correlateddifference vectors of either the vertical or horizontal or other type,joint quantization can offer useful compression.

In FIG. 41, base station eNB operations commence with eNB configurationBEGIN 3705 and configure subsets of subbands for each UEi in a step3710. Operations continue via eNB Main BEGIN 3715 to a step 3720 thatuses the feedback from each given UE to retrieve delta vectors from adelta codebook(s) using fed-back indices such as J_(u) and J_(s). A step3730 recovers the CQI (e.g., mean CQI) for the selected subbands and CQI(e.g., mean CQI) for the unselected subbands for each codeword r. Instep 3730 applied to TABLE 2 vertical reporting, the recovered mean CQIof selected subbands is _(s)F_(r)=_(s)D_(r)+_(s)F₁, and the recoveredmean CQI of un-selected subbands is _(u)F_(r)=_(u)Δ_(r)+_(u)F₁, appliedfor each codeword CW2, etc., i.e. for index r 2, . . . R. In step 3730applied to TABLE 3 horizontal reporting, the recovered mean CQI ofun-selected subbands is _(u)F_(r)=_(u)Δ_(r)+_(u)F₁, and the recoveredmean CQI of selected subbands is _(s)F_(r)=_(su)D_(r)+_(u)F_(r), appliedfor each codeword CW2, etc., i.e. for index r=1, . . . R. In step 3730applied to horizontal zig-zag reporting, the recovered mean CQI ofun-selected subbands is _(u)F_(r)=_(u)Δ_(r)+_(u)F₁, and the recoveredmean CQI of selected subbands is, e.g., _(s)F_(r)=_(s)D_(r)+_(s)F₁,applied for each codeword, r=1, 2, . . . R. In step 3730 applied toTABLE 4 reverse-horizontal reporting, the recovered mean CQI of selectedsubbands is _(s)F_(r)=_(s)D_(r)+_(S)F₁, and the recovered mean CQI ofun-selected subbands is _(u)F_(r)=_(s)F_(r)−_(su)D_(r), applied for eachcodeword CW2, etc., i.e. for index r=1, . . . R.

In FIG. 41, eNB step 3735 applies the recovered CQI information togetherwith the subband vector SV by a process such as in FIG. 43 to establishapproximated CQI information S_(i,j,r)˜=_(u)F_(r) or _(s)F_(r) on allsubbands j for all code words r and UEs i, ready for use by the eNBscheduler 2630. Operations proceed to the eNB scheduler 2630 to allocatesubbands to UEs followed by a precoder that establishes precodingmatrices for the UEs based on the subband allocations. In a step 2640,the base station eNB transmits over the downlink to the UEs using acomposite precoding matrix PM based on the precoding matrices thusestablished, whence eNB RETURN 3755 is reached.

Note that the various vertical, horizontal, etc. embodiments arestraightforwardly applied to all types of CQI reporting either in Best-mCQI reporting or in other types of CQI reporting. Instead of identifyinga datum as “u” or “s”, the other types have more than two subband indexvalues that are enumerated instead of having subscripts “u” and “s”.

Turning to FIG. 41A, a process flow for Delta Delta Best-m Average CQIreporting, with horizontal/vertical forms of the reporting, can becompared with FIG. 25A/B. In the UE, operations commence with UEconfiguration at a step 4005. The configuration type is found indecision step 4008 and can be established by UE or eNB. Then a step 4010configures the CQI reporting mode, and Delta Delta Best-m Average CQIreporting mode is illustrated. A succeeding step 4015 selects the bestsubbands and reports their positions by setting corresponding bits ofsubband vector SV(j)=1. Unselected subbands have SV(j)=0. Next in a step4020 generates the mean or median or wideband CQI _(s)F_(r) across theselected subbands for each codeword CW1, CW2, etc. Another step 4025generates mean or median or wideband CQI _(u)F_(r) for the unselectedsubbands for each codeword CW1, CW2, etc.

In FIG. 41A, differential encoding at a step 4030 generates deltas forthe selected subbands _(s)D_(r)=_(s)F_(r)−_(s)F₁ for each codeword CW2,etc., i.e. for index r 2, . . . R. Analogously, a step 4035 alsogenerates deltas for the unselected subbands _(u)Δ_(r)=_(u)F_(r)−_(u)F₁for each codeword CW2, etc., i.e. for index r=2, . . . R. Then a step4040 generates Delta Deltas in various embodiments described insucceeding paragraphs for FIG. 41A. Some embodiments at step 4040additionally joint quantize the Delta Deltas and output a codebook indexJ_(DD) for them along with a codebook index J_(s) for delta _(s)D_(r) ora codebook index J_(u) for delta _(s)Δ_(r). After step 4040 a UE RETURN4055 is reached.

For the Delta Delta embodiments of FIG. 41A, uplink feedback 4070 isprovided in any of a variety of embodiments described next in the sameorder as analogous embodiments of FIG. 41. A first embodiment of TABLE2A, is called vertical Delta Delta CQI reporting herein and applicablefor rank 3 or higher. The CQI report vector is expressed as (SV, _(u)F₁,_(s)F₁, _(u)Δ₂, _(s)D₂, _(u)ΔΔ_(r), _(s)ΔD_(r)). In words, the CQIreport vector has subband vector SV, the FIG. 21 mean/median/widebandcollective CQI _(s)F₁ for the selected subbands for codeword CW1 and theFIG. 21 mean/median/wideband collective CQI _(u)F₁ for the unselectedsubbands for codeword CW1. The CQI report also includes the spatial CQIdifference in _(s)D₂ between collective CQI _(u)F₂ for the CW2 selectedsubbands relative to _(s)F₁ for codeword CW1. The CQI report further hasthe spatial CQI difference _(u)Δ₂ for codeword CW2 unselected subbandsrelative to CQI _(u)F₁ for the CW1 unselected subbands. For the highercode words CW3, etc., Delta Deltas are provided, e.g.,_(u)ΔΔ_(r)=_(u)Δ_(r)−_(u)Δ₂ and _(s)ΔD_(r)−_(s)D_(r)−_(s)D₂ for codewordindex r=3, . . . R. If spatial Delta CQIs _(s)D_(r) are quite similar inmagnitude across code words r, vertical Delta Delta CQI reportingdelivers compression because the quantities are represented with just afew bits.

TABLE 2A BEST-m CQI REPORTING (“VERTICAL Δ Δ”) Unselected SelectedSub-bands Sub-bands CW1 _(u)F₁ _(s)F₁ CW2 _(u)Δ₂ _(s)D₂ CW3, etc. _(u)ΔΔ_(r) _(s)Δ D_(r)

A second Delta Delta embodiment related to FIG. 41A is shown in TABLE3A, and a CQI report vector is expressed as (SV, _(u)F₁, _(u)Δ_(r),_(su)D₁, ΔD_(r)). In words, the CQI report vector has subband vector SV,the FIG. 21 mean/median/wideband collective CQI _(u)F₁ for theunselected subbands for codeword CW1. (_(s)F₁ need not be explicitlyreported.) The CQI report also includes the spatial CQI differences_(u)Δ_(r) relative to CQI _(u)F₁ for the unselected subbands forcodeword CW1. Horizontal CQI Deltas are generated and expressed by_(su)D_(r)=_(s)F_(r)−_(u)F_(r). The CQI report includes _(su)D₁ forcodeword CW1. Horizontal CQI Delta Deltas are generated and fed back asexpressed by _(su)ΔD_(r)=_(su)D_(r)−_(su)D₁ for each codeword index r=2,. . . R. When Delta CQIs _(su)D_(r) are not small but quite similar inmagnitude across codewords r, horizontal Delta Delta CQI reporting ofTABLE 3A delivers compression because the Delta Deltas _(su)ΔD_(r) aresmall and easily represented with just a few bits. Variants of thesecond embodiment _(su)D′_(r)=_(s)F_((r+1)modR)−_(u)F_(r) for eachcodeword, r=1, 2, . . . R, also can provide useful correlation in azig-zag or other scanning pattern for generating the spatial CQIdifferences, whereupon the Delta Delta provides compression using aprocess expressed by _(su)ΔD′_(r)=_(su)D′_(r)−_(su)D′₁. Thus, thescanning process teachings herein for FIGS. 32-37 are not only usefulfor generating the order of uplink transmission of CQI reporting databut also useful for independently or dependently establishing pairs ofvalues for Delta Delta and/or the order of transmission of DeltaDelta-based CQI reporting data.

TABLE 3A BEST-m CQI REPORTING (“HORIZONTAL Δ Δ”) Unselected SelectedSub-bands Sub-bands CW1 _(u)F₁ _(su)D₁ CW2, etc. _(u)Δ_(r) _(su)Δ D_(r)

In a third embodiment related to FIG. 41A and shown in TABLE 4A, a CQIreport vector is expressed as follows: (SV, _(s)F₁, _(s)D_(r), −_(su)D₁,−_(su)ΔD_(r)). In words, the CQI report vector has subband vector SV,the FIG. 21 mean/median/wideband collective CQI _(s)F₁ for the selectedsubbands for codeword CW1. (_(u)F₁ need not be explicitly reported.) TheCQI report also includes the spatial CQI differences _(s)D_(r) relativeto CQI _(s)F₁ for the selected subbands for codeword CW1. Areverse-horizontal Delta CQI is generated by a process expressed by_(us)D_(r)=−_(su)D_(r)=_(u)F_(r)−_(s)F_(r) that delivers CQI differencesin a given row for each codeword, r=1, 2, . . . R. One of these CQIdifferences is fed back from UE to eNB, e.g. −_(du)D₁. Since the reversehorizontal CQI differences _(us)D_(r)=−_(su)D_(r)=_(u)F_(r)−_(s)F_(r)may have magnitudes of differences that could be small, if compressed,yet are likely to have substantial spatial correlation across code wordsanyway, a difference encoding of these differences (Delta Delta) isgenerated and fed back by a reverse-horizontal Delta Delta processexpressed by

−_(su)ΔD_(r)=_(su)D₁−_(su)D_(r) for each codeword index r=2, . . . R.

TABLE 4A BEST-m CQI REPORTING (“REVERSE-HORIZONTAL Δ Δ”) UnselectedSelected Sub-bands Sub-bands CW1 −_(su)D₁ _(s)F₁ CW2, etc. −_(su)Δ D_(r)_(s)D_(r)

In a fourth embodiment category related to FIG. 41A, any of the firstthree embodiments are subjected to joint quantization in step 4040. Forinstance, the CQI report vector has the form (SV, _(u)F₁, _(su)D₁,J_(u), J_(DD), R) or (SV, _(s)F₁, −_(su)D₁ J_(s), J_(DD), R) forhorizontal reporting in TABLE 3A or 4A. J_(DD) signifies a codebookindex resulting from joint quantization of the horizontal Delta Deltavector _(su)ΔD_(r) or −_(su)ΔD_(r). (The codebook index is likely to beindependent of the plus/minus sign while the codebook entry has theplus-minus sign.) For substantially correlated difference vectors ofeither the vertical or horizontal or other type, joint quantization canoffer additional useful compression.

In FIG. 41A, base station eNB operations commence with eNB configurationBEGIN 4105 and configure subsets of subbands for each UEi in a step4110. Operations continue via eNB Main BEGIN 4115 to a step 4120 thatuses the feedback from each given UE to retrieve delta vectors from adelta codebook(s) using fed-back indices such as J_(DD) and/or J_(u) andJ_(s). In step 4120 applied to vertical reporting TABLE 2A, recoveredDelta _(s)D_(r)=_(s)D₂+_(s)ΔD_(r) and recovered Delta is expressed by_(u)Δ_(r)=_(u)Δ₂+_(u)ΔΔ_(r) for index r=3, . . . R. In correspondingstep 4130, the vertically recovered mean CQI of selected subbands is_(s)F_(r)=_(s)D_(r)+_(s)F₁, and the recovered mean CQI of un-selectedsubbands is _(u)F_(r)=_(u)Δ_(r)+_(u)F₁, applied for each codeword CW2,etc., i.e. for index r=2, . . . R. In step 4120 applied to horizontalreporting TABLE 3A, recovered Delta _(su)D_(r)=_(su)D₁+_(su)ΔD_(r) forindex r=2, . . . R. The corresponding step 4130 horizontally recoveredmean CQI of selected subbands is _(s)F_(r)=_(su)D_(r)+_(u)F_(r), appliedfor each codeword CW2, etc., i.e. for index r=1, . . . R, and obtainedafter computing the recovered mean CQI of un-selected subbands_(u)F_(r)=_(u)Δ_(r)+_(u)F₁. In step 4120 applied to horizontal zig-zagreporting, recovered Delta _(su)D′_(r)=_(su)D′₁+_(su)ΔD′_(r) for indexr=2, . . . R. The corresponding step 4130 horizontal zig-zag recoveredmean CQI of selected subbands is_(s)F_((r+1)modR)=_(su)D′_(r)+_(u)F_(r), applied for each codeword, r=1,2, . . . R, and obtained after computing the recovered mean CQI ofun-selected subbands _(u)F_(r)=_(u)Δ_(r)+_(u)F₁. In step 4120 applied toreverse-horizontal reporting, recovered Delta_(su)D_(r)=_(su)D₁+_(su)ΔD_(r) for index r=2, . . . R. The correspondingstep 4130 reverse-horizontal recovered mean CQI of selected subbands is_(s)F_(r)=_(s)D_(r)+_(s)F₁, and the recovered mean CQI of un-selectedsubbands is _(u)F_(r)=_(s)F_(r)−_(su)D_(r), applied for each codewordCW2, etc., i.e. for index r=1, . . . R.

In FIG. 41A, a step 4135 applies the recovered CQI information togetherwith the subband vector SV by a process such as in FIG. 43 so that theCQI information S_(i,j,r) on all subbands for all code words r and UEsi, is ready for use by the eNB scheduler at step 4140. Operationsproceed to the eNB scheduler to allocate subbands to UEs followed by aprecoder that establishes precoding matrices for the UEs based on thesubband allocations. In a step 4150, the base station eNB transmits overthe downlink to the UEs using a composite precoding matrix PM based onthe precoding matrices thus established whence eNB RETURN 4155 isreached.

In FIG. 42, a process flow for Best-m Individual Mean-Delta CQIreporting with joint quantization and TABLE 5 Best-m horizontal or(TABLE 6 Best-m vertical) forms of the CQI feedback can be compared withFIGS. 27A/B and FIG. 28A/B. In the UE, operations commence with UEconfiguration at a step 4405. The configuration type is found in adecision step and established by UE or eNB. The selected subbands aredetermined as in FIG. 7. Then a step 4410 configures the CQI reportingmode, e.g., Best-m Individual Mean-Delta CQI reporting mode, whereupon aMain Begin 4415 is reached. The process symbols are illustrated in TABLE5. (Alternative process operations are described by sentences inparentheses ( ) and alternative process symbols are illustrated in TABLE6.) Next a step 4420 generates the mean or median or wideband CQIF_(0,r) for each codeword CW1, CW2, etc. Differential encoding at step4420 generates wideband deltas ΔF_(0,r)=F_(0,r)−F_(0,1) for eachcodeword CW2, etc., i.e. for index r=2, . . . R. (Alternatively,selected-subband deltas only for CW1 are generated instead, asrepresented by Δ_(j,i)=S_(j,1)−F_(0,1).) Next, a step 4430 generatesselected-subband deltas expressed by Δ_(j,r)=S_(j,r)−F_(0,r) for eachcodeword CW2, etc., i.e. for selected subbands j indicated by subbandvector SV (FIG. 43) and for index r=2, . . . R. (Alternatively at step4430, subband spatial deltas are generated instead, as represented byD_(j,r)=S_(j,r)−S_(j,1), for selected subbands j and code words indexedr=2, . . . R.) Then a step 4440 joint quantizes the subband deltasΔ_(j,r) and repeatedly uses a subband delta vector codebook and outputscodebook index J_(r) for each index r=1, 2, . . . R (or joint quantizessubband spatial deltas D_(j,r) instead and repeatedly uses a subbandspatial delta vector CQI codebook and outputs codebook index J_(j) foreach of the selected best-m subbands j). Various forms of the CQIfeedback 4470 are depicted in FIG. 42. After step 4440 a UE RETURN 4455is reached.

TABLE 5 BEST-m MEAN-DELTA CQI REPORTING (“HORIZONTAL”) Mean/Median/Wideband Sub-bands CW1 F_(0,1) Δ_(j,1) CW2, etc. Δ F_(0,r) Δ_(j,r)

TABLE 6 BEST-m MEAN-DELTA CQI REPORTING (“VERTICAL”) Mean/Median/Wideband Sub-bands CW1 F_(0,1) Δ_(j,1) CW2, etc. Δ F_(0,r) D_(j,r)

In FIG. 42, base station eNB operations commence with eNB configurationBEGIN 4505 and configure subsets of subbands for each UEi in a step4510. In cases where eNB configures Directed Mode and configures andsends subband vector SV of FIG. 43 to identify the selected subbands forUEi in accordance with the subsets, then UE has no need to feed back theSV that eNB already has established. Operations continue via eNB MainBEGIN 4515 to a step 4520 that uses the feedback 4470 from each given UEto retrieve delta vectors Δ_(i,j,r) from a delta codebook(s) usingfed-back indices J_(r). (Alternatively at step 4520, UE retrievesspatial delta vectors D_(i,j,r) using fed-back indices J_(j).) A step4525 recovers the CQI (e.g., mean/median/wideband CQI) for each codewordusing a process expressed by F_(i,0,r)=ΔF_(i,0,r)+F_(i,0,1), applied foreach codeword CW2, etc., i.e. for index r=2, . . . R. (Alternatively instep 4525, the CQIs for the subbands j of CW1 are recovered using aprocess S_(i,j,1)=Δ_(i,j,1)+F_(i,0,1), applied for codeword CW1.) In astep 4530, the CQIs for the subbands j of the other codewords arerecovered using a horizontal recovery processS_(i,j,r)=Δ_(i,j,r)+F_(i,0,r), applied for each codeword CW2, etc., i.e.for selected subbands j indicated by subband vector SV (FIG. 43) and forindex r=2, . . . R. (Alternatively in step 4530, in a vertical recoveryprocess use S_(i,j,r)=D_(i,j,r)+S_(i,j,1), for the selected subbands jand for the code words indexed r=2, . . . R.) Alternatively, theposition of the selection subbands, instead of being reported using thebitmap vector SV, is jointly quantized and reported using log₂(C_(M)^(m)) bits. In a process that uses CQI of a reference subband k(r) as areference REF instead of mean/median/wideband CQI, a step 4534 recoversthe position k(r) and a step 4538 establishes CQI at that position, i.e.S_(i,j=k(r),r)=F_(i,0,r).

In FIG. 42, a step 2630 applies the recovered CQI information so thatthe CQI information S_(i,j,r) on all subbands for all code words r andUEs i, for use by the eNB scheduler. Operations by eNB scheduler 2630allocate subbands to UEs followed by a precoder that establishesprecoding matrices for the UEs based on the subband allocations. In astep 2640, the base station eNB transmits over the downlink to the UEsusing a composite precoding matrix PM based on the preceding matricesthus established. eNB RETURN is reached at step 4555.

In FIG. 42A, a process flow for Best-m Individual Mean-Delta & DeltaDelta CQI reporting, with joint quantization of the Delta Delta andwherein eNB counts the feedback, can be compared with FIG. 31A/B. In theUE, operations commence with UE configuration at a step 4805. Theconfiguration type is found in a decision step and established by UE oreNB. The selected subbands are determined as in FIG. 7. Then a step 4810configures the CQI reporting mode, e.g., Best-m Individual Mean-Delta &Delta Delta CQI reporting mode, whereupon a Main Begin 4815 is reached.The process symbols are illustrated in TABLE 6A. Next a step 4820generates the mean or median or wideband CQI F_(0,r) for each codewordCW1, CW2, etc. Differential encoding at step 4820 generates widebanddeltas ΔF_(0,r)=F_(0,r)−F_(0,1) for each codeword CW2, etc., i.e. forindex r=2, . . . R. Next, for the selected subbands j indicated bysubband vector SV (FIG. 43), a step 4830 generates subband deltasD_(j,r)=S_(j,r)−F_(0,r), for each codeword CW1, CW2, etc., i.e. forindex r=1, 2, . . . R. Then step 4830 forms the Delta Deltas by aprocess represented by ΔD_(j,r)=D_(j,r)−D_(j,1) for the selectedsubbands j and the code words indexed r=2, . . . R. These can be fedback directly as shown in one form of the uplink feedback 4870 of FIG.42A. Or further operation in a step 4840 joint quantizes the subbanddelta vector D_(j,1) and/or also joint quantizes each Delta Delta vectorΔD_(j,r), using a Delta Delta vector codebook. Step 4840 outputs DeltaDelta codebook index J_(r) for r=2, . . . R for another form of theuplink feedback 4870. Step 4840 also outputs Delta codebook index J₁ forindex r=1. Rank R to which the reporting pertains is implicit in thenumber of fed-back indices. After step 4840 a UE RETURN 4855 is reached.

For brevity of description, an alternative Delta Delta process hasquantities in TABLE 5A Best-m Individual CQI reporting analogous toBest-m Average CQI reporting TABLE 2A already described.

TABLE 5A BEST-m MEAN-DELTA CQI REPORTING (“VERTICAL Δ Δ”) Mean/Median/Wideband Sub-bands CW1 F_(0,1) Δ_(j,1) CW2, etc. Δ F_(0,r) Δ_(j,r) CW3,etc. _(u)Δ Δ_(r) Δ D_(j,r)

TABLE 6A BEST-m MEAN-DELTA CQI REPORTING (“HORIZONTAL Δ Δ”) Mean/Median/Wideband Sub-bands CW1 F_(0,1) D_(j,1) CW2, etc. Δ F_(0,r) Δ D_(j,r)

In FIG. 42A, base station eNB operations commence with eNB configurationBEGIN 4905 and configures subsets specifying selected subbands for eachUEi in a step 4910. In cases where eNB configures Directed Mode andconfigures and sends subband vector SV of FIG. 43 to identify theselected subbands for UEi in accordance with the subsets, then UE has noneed to feed back the SV that eNB already has established. eNBdetermines rank R either from its own configuration of UEi or bycounting the number of the CQI report indices sent over the uplink fromUEi. Operations continue via eNB Main BEGIN 4915 to a step 4920 thatuses the report from each given UEi to retrieve the delta vectorD_(i,j,1), from a delta codebook(s) using fed-back index J₁. eNB alsouses fed-back indices J_(r) to access a Delta Delta codebook and therebyrecover ΔD_(i,j,r) for UEi. In step 4924 applied to Best-m Delta Deltareporting of TABLE 6A, the recovered wideband CQI isF_(i,0,r)=ΔF_(i,0,r)+_(i,0,1), applied for each codeword CW2, etc., i.e.for index r=2, . . . R. In a step 4928, the Delta subset is recovered bya process expressed by D_(i,j,r)=ΔD_(i,j,r)+D_(i,j,1). In step 4930, therecovered CQI of subbands are obtained by a processS_(i,j,r)=F_(i,0,r)+D_(i,j,r) for each selected-subband index j and foreach codeword CW2, etc., i.e. for index r=1, . . . R, for each UEi. Forunselected subbands k, the process establishes S_(i,k,r)=F_(i,0,r) usingwideband CQIs F_(i,0,r). In FIG. 42A, a step 4940 applies the recoveredCQI information so that the CQI information S_(i,j,r) on all subbandsfor all code words r and UEs i, is ready for use by the eNB scheduler.The eNB scheduler 2630 allocates subbands to UEs. In a step 4950, aprecoder establishes precoding matrices for the UEs based on the subbandallocations. Base station eNB transmits over the downlink to the UEsusing a composite precoding matrix PM based on the precoding matricesthus established, whence eNB RETURN 4955 is reached.

Description turns to various matrix-based processes for CQI reporting. Amatrix-based process embodiment for Mean-Delta & ΔΔCQI Reportingresembles the process of FIG. 38 or FIG. 42A and TABLE 6A. In the UE, aprocess for generating a CQI reporting matrix Φ (dimensions R×(M+1))includes a rank-related differencing matrix Δ (e.g., TABLE 7)matrix-premultiplied times a matrix S of subband CQIs that is in turnmatrix post-multiplied by a weight matrix W, as expressed by thefollowing process embodiment equation Φ=ΔSW. (Dimensionally,R×(M+1)=product of R×R, R×M, M×(M+1) in one example.) Subband CQI matrixS has rows of subband CQIs for each spatial codeword, as in FIG. 31A/B.Weight matrix W in one example is shown in Mean-Delta TABLE 8. Ingeneral, however, weight matrix W represents any compression processexpressible by matrix multiplication and applicable to rank as low asone (R=1), except that it is applied here also for MIMO rank of two ormore (R>=2). The product SW compactly expresses the mean CQIs for thecodewords respectively, as well as subband CQI differences (Deltas)relative to the mean for their codeword. The pre-multiplying by matrix Δboth delivers differentially encoded means relative to the mean CQI fora first codeword and also delivers the Delta Deltas of TABLE 6A. Thedifferencing matrix Δ is selected as in TABLE 7 or otherwise, and asuitable differencing matrix Δ is represented by a square matrix R×Rhaving dimensions each equal to the rank R and composed of blocks asfollows: 1) upper left hand one element (1, unity), 2) zeroes in rest offirst row, 3) minus-ones (−1's) in rest of first column, 4) identitymatrix block filling the rest of the matrix, e.g., see TABLE 7.

TABLE 7 DIFFERENCING MATRIX Δ (R × R)   1 0 0 0 . . . 0 −1 1 0 0 0 −1 01 0 0 −1 0 0 1 0 . . . . . . −1 0 0 0 . . . 1

TABLE 8 MEAN-DELTA WEIGHT MATRIX (M × (M + 1), one example of W) 1/M 1 −1/M −1/M . . . −1/M 1/M −1/M 1 − 1/M −1/M . . . . . . 1/M −1/M −1/M . .. 1 − 1/M

CQI reporting matrix Φ is scanned out and fed back to eNB in any desiredorder, applying the CQI feedback scanning embodiments of FIGS. 32-37 tothe CQI reporting matrix Φ itself. Alternatively, one or more parts orall of the CQI reporting matrix Φ is/are vector joint quantized and theresults of joint quantization scanned out and fed back to eNB in anyappropriate manner, applying the embodiments of FIGS. 32-37 to the CQIreporting matrix Φ in parts and joint-quantized vectors thereof. Some ofthese alternatives are also depicted in the uplink feedback from the UEside in FIGS. 38-42A.

Base station eNB includes a complementary process embodiment, as inFIGS. 38-42A on the eNB side, that recovers Subband CQI matrix S fromCQI reporting matrix Φ. The recovery process uses the matrix inverse ofdifferencing matrix Δ matrix-premultiplied times the matrix of CQIfeedback Φ that is in turn matrix post-multiplied by the matrixright-inverse (symbolized −1′) of generally non-square weight matrix W,as expressed by the process embodiment equation S=Δ⁻¹ΦW^(−1′).(Dimensionally, R×M=product of R×R, R×(M+1), (M+1)×M correspondingly.)The above matrix formulation is believed to be relatively robust in thatit can be applied to systems with a variety of numbers M of subbands,and a variety of rank numbers R. The weight matrix W is customizedsomewhat in entries and dimensions for any selected compressionapproach, such as Mean-Delta, or Reference-Delta, or Pairwise Delta foradjacent subbands, or Transform using orthogonal or nonorthogonal basisvectors, etc.

For an example of FIG. 41A Best-m Average CQI reporting, the matrixprocess is slightly augmented (or, to put it another way, the weightmatrix W is specified in more detail and replaced by a product ofmatrices, Wσ) because the reporting on subbands is grouped together forselected subbands and unselected subbands. In the UE, a process forBest-m (Horizontal ΔΔ) CQI reporting Φ of TABLE 3A includes arank-related R×R differencing matrix Δ (TABLE 7) matrix-premultipliedtimes a matrix S of subband CQIs that is in turn matrix post-multipliedby a weight matrix W (TABLE 8) and further augmented bypost-multiplication by a 2×2 matrix σ, as expressed by the processembodiment equation Φ=ΔS Wσ. (Dimensionally, R×2=product of R×R, R×M,M×2, 2×2. The 2×2 matrix σ has first row [1 −1], second row [0 1].)

Not only does CQI Reporting matrix Φ have dimensions R×2 for FIG. 41Aand therefore is considerably compressed compared to R×M CQI matrix S,but also the differencing process further compresses the dynamic rangeto confer highly efficient CQI feedback. For this form of Best-m AverageCQI reporting, the M×2 weight matrix W is a transpose of the matrixhaving first row (1/(M−m)) [[1]−[SV]] and second row (1/m)[SV], where[SV] is the FIG. 43 subband vector SV of positions of m selectedsubbands, M is the total number of subbands, (M−m) is the number ofunselected subbands, and [1] is a row of all ones. (Matrix σ column [10]^(T) represents the operation that focuses on TABLE 3A reportingcolumn [_(u)F₁, _(u)Δ_(r)]^(T), and second column [−1 1]^(T) representsa differencing operation to get intermediate _(su)D_(r).Pre-multiplication by matrix Δ then delivers CQI reporting matrix Φ ofTABLE 3A.)

In base station eNB, a complementary Best-m Horizontal recovery processembodiment to recover Best-m Subband CQI matrix product SW from CQIreporting matrix Φ again uses the matrix inverse Δ⁻¹ of differencingmatrix matrix-premultiplied times the matrix of CQI reporting matrix Φ.Now the process is augmented by matrix post-multiplying the inverse σ⁻¹of matrix sigma, and recovers Best-m subband CQI matrix product SW asexpressed by process embodiment equation SW=Δ⁻¹ Φσ⁻¹. (Dimensionally,R×2=product of R×R, R×2, 2×2. 2×2 matrix σ⁻¹ has first row [1 1], secondrow [0 1]. First column [1 0]^(T) focuses on recovery of mean CQIs foreach rank or other references REF for each rank. Second column [1 1]^(T)enables addition to recover from some differencing.)

Computational optimizations such as pre-computing some of the inversesand products are readily provided. Note also that where ordinarysubtractions inside the matrix operations can be replaced in general byspecified functions f_(diff)( , ) and ordinary additions can be replacedin general by specified functions f_(add)( , ) such as by reversing asign of an argument value inside f_(diff)( , ) or otherwise as desired.Some embodiments use matrix operations to accomplish differentialcompression in UE and reconstruction in eNB along the lines shown orindicated in FIGS. 10-42A. Notice in the matrix operations thatpost-multiplication of CQI matrix S by weight matrix W provides codewordspecific compression. Pre-multiplication by matrix Δ times SW providesdifferencing across spatial codewords. Some matrix embodiments hereinoperate on the original CQIs S_(jr) as a CQI image array and compressthat CQI image array S_(jr) by using any suitable image transform (2-D).

Various forms of parameterization of vectors are suitably employed forCQI reporting. Embodiments for parameterization of vectors includestructures and processes for parameterization of CQI vectors acrosssubbands in a given codeword or across codewords in a given subband,parameterization of CQI difference vectors across subbands in a givencodeword or across codewords in a given subband, and/or parameterizationof delta delta CQI vectors across subbands in a given codeword or acrosscodewords in a given subband. Positions of zero crossings, widths ofpositive runs, widths of negative runs, and other parameters of suchvectors are suitably encoded for parameterized CQI reporting acrosscodewords, across subbands, and across scanning patterns (e.g. in FIGS.32-37).

Note that all the above figures/numerical values are exemplary and forillustrative purposes. Various generalizations of the above approachesare specified for any size of sub-band, different number of sub-bandswithin the system bandwidth, different sub-band sizes, etc. Several CQIreporting embodiments accommodate MIMO-OFDMA systems with multiplecodewords (layers) transmitted in the spatial domain simultaneously.Specifically, the following CQI reporting processes and structures applyfor Wideband CQI reporting, eNB configured CQI feedback, UE-selectedsub-band CQI feedback, Scanning-based CQI feedback, and other forms ofCQI feedback. Any combination, variation, or generalization of the aboveembodiments can be applied in CQI feedback for MIMO OFDMA.

While the above embodiments are given in the context of an OFDM/OFDMAsystem, it is also contemplated to apply the techniques taught in thisinvention to some other data modulation or multiple access schemes thatutilize some type of frequency-domain multiplexing. Some examplesinclude but are not limited to the classical frequency-domain multipleaccess (FDMA), single-carrier FDMA (SC-FDMA), and multi-carrier codedivision multiple access (MC-CDMA).

FIG. 43 is a flow diagram for depicting a process embodiments for eNBreconstructing original CQIs S_(jr), or intermediately reconstructingCQI differences D_(jr), from the subband vector SV generated in Best-mCQI reporting. FIG. 43 provides substeps for use in FIG. 41 step 3735 orFIG. 41A step 4135, or FIG. 42 steps 4530-4538 or FIG. 42A step 4930.Operations in FIG. 43 commence with a BEGIN 5105 that sets codewordindex r=1, and operations proceed to a step 5110 that initializesindices j=1 and L=1. A decision step 5120 is part of a process ofscanning subband vector SV. For the A-suffixed FIGS. 25A-31A, SV(j) isindependent of codeword index r. For the B-suffixed FIGS. 25B-31B,SV(j,r) is fed back for each spatial codeword r and used in FIG. 43.(The dependence on codeword index r is shown in FIG. 43 and may beomitted for embodiments where it is not applicable.) A particularexample of a 10-element subband vector SV is shown below the flow.Decision step 5120 determines whether a given subband vector elementSV(j,r) is one (1) or not. If not, the full-length (M) CQI, ordifferential CQI, vector D of FIG. 43 is set equal to zero (0) atelement j so that D(j,r)=0 at step 5125. (In some Best-m Averageembodiments, e.g. FIG. 41, instead set D(j,r) equal to the differentialencoding _(u)Δ_(r) or CQI _(u)F_(r) at step 5125 for the unselectedsubbands.) Then a step 5130 increments index j. Then a decision step5140 determines by the criterion j>jmax whether the entire subbandvector SV has been scanned in a configured scanning pattern such as inany one of FIGS. 32-37. If not, operations loop back to decision step5120. At decision step 5120, if the given subband vector element SV(j,r)is one, then operations proceed to a step 5160 to access shortdifferential CQI vector DV(L,r) element L and multiply to generate afull-length differential CQI vector element D(j,r)=SV(j,r)×DV(L,r). Someembodiments simply use the logic IF SV(j,r)=1, THEN D(j,r)=DV(L,r) atthis point. (Note: D(j,r) and DV(L,r) correspond to and are suitablymade to take the position of various CQI S_(ijr) or S_(ikr) designationsor differential D or A designations used in FIG. 41 step 3735, FIG. 41Astep 4135, FIG. 42 steps 4530-4538 and FIG. 42A step 4930.) If the scanacross the short CQI, or differential CQI, vector DV is completed,L=Lmax at a decision step 5170 and operations reach decision step 5185.(Lmax=m, the number of Best-m selected subbands, and is a constant insome embodiments or is a function Lmax(r) of codeword r in some otherembodiments.) Otherwise, operations proceed from decision step 5170 to astep 5180 that increments the index L that scans the short differentialCQI vector DV. (Both steps 5170 and 5180 are omitted for Best-m AverageCQI reporting of FIGS. 24A/B, 25A/B, 41/41A.) Operations go from step5180 to step 5130 and the process goes on as already described. If Yesat step 5140 or Yes at step 5170, then step 5185 determines whethercodeword index r=Rmax, i.e. equals rank R. In Joint Sub-band Selectionin FIG. 25A, Rmax=1 and operations at step 5185 immediately determinethat r=Rmax and pass directly to a RETURN 5195. In Independent Sub-bandSelection FIG. 25B, operations go from step 5185 to a step 5190 toincrement codeword index r=r+1 and loop back to step 5110. In duecourse, all the codewords r are handled in FIG. 43, and step 5185determines that codeword index now has r=Rmax, and operations reach theRETURN 5195.

Note that some other embodiments statically or dynamically control theorder of looping through the indices according to a configured scanningpattern as identified by a scanning code and discussed and connectionwith FIGS. 32-37 among other Figures. In some embodiments or variants ofFIG. 43, the scanning process includes a scanning loop over aone-dimensional scanning pattern index (e.g., s=1, 2, 3, . . . N, whereN=RM) in the loop kernel has a mapping function F(s)==(j, r) from theone-dimensional scanning pattern index to generate indices r, j in atwo-dimensional discrete index value space (r, j) for the subbands j ofeach codeword r, where 1≦r≦R and 0≦j≦M. The loop kernel further includesa computation and/or read or write to storage that involves variables asa function of the indices in two-dimensional discrete index value space(j, r). In terms of FIG. 43, an example of the scanning process of FIGS.32-37 provides the mapping function F(s)==(j, r) ahead the loop kernel5120, 5125, 5160 that is written in terms of indices (j, r). The mappingfunction F(s) instantiates the scanning pattern and is retrieved from astored codebook in memory indexed by the scanning code. The mappingfunction and the loop kernel are embedded together in a one-index loopon index s. When the loop executes, its operations are performedaccording to the scanning pattern. This type of scanning patternprocess, such as by FIGS. 32-37, in some embodiments is similarlyapplied to any the processes of FIGS. 38-42A wherever they loop onindices (r,j) to instantiate a configured scanning pattern therein.

U.S. patent application “Precoding Matrix Feedback Processes, Circuitsand Systems,” Ser. No. 12/188,767 (TI-65218), incorporated herein byreference, shows an improved communications system 1000 with systemblocks and one or more integrated circuits for system on chip asdescribed therein and improved with any one, some or all of the circuitsand subsystems shown in various Figures of the drawing herein. Any orall of the system blocks, such as cellular mobile telephone and datahandsets 1010 and 1010′, a cellular (telephony and data) base station1050, a WLAN AP (wireless local area network access point, IEEE 802.11or otherwise) 1060, a Voice over WLAN Gateway 1080 with user voice overpacket telephone 1085 (not shown), and a voice enabled personal computer(PC) 1070 with another user voice over packet telephone (not shown),communicate with each other in communications system 1000. Instructionsfor various processes disclosed herein are suitably stored in whole orin part in flash memory, or volatile or nonvolatile memory on or offchip relative to microprocessor core(s) or other processor block(s).Instructions are suitably conveyed to the device or system inmanufacture or in use, by some tangible medium of storage such asoptical disc, magnetic disk, flash drive, etc., or by download fromanother system such as a server and/or website.

Aspects (See Notes Paragraph at End of this Aspects Section.)

1A4A. The electronic device claimed in claim 4 wherein said firstcircuit is also operable to form a reporting representation identifyingwhich subbands are selected. 1B. The electronic device claimed in claim1 wherein the first reference CQI includes a mean, median, or widebandCQI for the first spatial codeword and the second reference CQI includesa mean, median, or a wideband CQI for the second spatial codeword. 1C.The electronic device claimed in claim 1 further comprising pluralantennas, and a transmitter to transmit a signal from at least one ofsaid plural antennas communicating the CQI report in response to thesecond circuit, and a user interface coupled to said first circuit,wherein said first circuit is coupled to process received signals fromsaid plural antennas, whereby to form a communication device.

1P. A process of operating an electronic device, the process comprisinggenerating at least a first and a second channel quality indicator (CQI)vector associated with a plurality of subbands for each of at leastfirst and second spatial codewords respectively; generating a first anda second reference CQI for the first and second spatial codewords, and afirst and a second differential subbands CQI vector for each spatialcodeword, and a differential between the second reference CQI and thefirst reference CQI; and forming a CQI report derived from the first andthe second differential subbands CQI vector for each spatial codeword aswell as the differential between the second reference CQI and the firstreference CQI. 1PA. The process claimed in claim 1P wherein the firstdifferential subbands CQI vector includes at least one difference of asubband CQI in the first CQI vector relative to the first reference CQI,and the second differential subbands CQI vector includes at least onedifference of a subband CQI in the second CQI vector relative to thesecond reference CQI. 1PB. The process claimed in claim 1P wherein thefirst differential subbands CQI vector includes at least one differenceof at least one subband CQI in the second CQI vector pairwise relativeto at least one subband CQI in the first CQI vector. 1PC. The processclaimed in claim 1P wherein the first differential subbands CQI vectorincludes a difference of at least one CQI for selected subbands relativeto the first reference CQI, and the second differential subbands CQIvector includes a difference of at least one CQI for selected subbandsrelative to the second reference CQI.

6A8A. The CQI report scanning circuit claimed in claim 8 wherein whereinsaid first circuit is operable to determine at least one selectedsubband for each spatial codeword and the first reference CQI includes aCQI for unselected subbands for the first spatial codeword and thesecond reference CQI includes a CQI for unselected subbands for thesecond spatial codeword.

6P. A process of operating a CQI report scanning circuit, the processcomprising generating a CQI report derived from at least a first and asecond channel quality indicator (CQI) vector associated with aplurality of subbands for each of at least first and second spatialcodewords respectively, configurably establishing a scanning pattern forthe CQI report across the spatial codewords and subbands, and initiatingtransmission of a signal communicating the CQI report according to theconfigurably established scanning pattern. 6PA. The process claimed inclaim 17 wherein the generating includes determining at least oneselected subband for each spatial codeword, and said initiatingtransmission includes executing the configurably established scanningpattern for CQI reporting for each selected subband prior to CQIreporting for unselected subbands.

9A. The CQI reporting circuit claimed in claim 9 wherein the CQI reportis derived using at least one of: 1) an entry index of a vectorcodebook, 2) a transform, 3) a parameterization. 9B. The CQI reportingcircuit claimed in claim 9 wherein the first circuit is further operableto determine at least one selected subband for each spatial codeword andsaid signal generated by the second circuit includes informationidentifying the at least one selected subband. 9C. The CQI reportingcircuit claimed in claim 9 further comprising plural antennas, and atransmitter to transmit a signal from at least one of said pluralantennas communicating the CQI report in response to the second circuit,and a user interface coupled to said first circuit, wherein said firstcircuit is coupled to process received signals from said pluralantennas, whereby to form a communication device.

9P. A process of operating a CQI reporting circuit, the processcomprising generating at least a first and a second channel qualityindicator (CQI) vector associated with a plurality of subbands for eachof at least first and second spatial codewords respectively and a firstand a second differential subbands CQI vector for each of the first andsecond spatial codewords respectively, and generating a CQI report basedon a vector differential between the second differential subbands CQIvector and the first differential subbands CQI vector. 9PA. The processclaimed in claim 9P wherein the CQI report also includes informationbased on at least one of the first or second differential subbands CQIvector. 9PB. The process claimed in claim 9P wherein the first circuitis operable to generate a first and a second reference CQI for the firstand second spatial codewords respectively, and the CQI report includesinformation based on a said reference CQI for at least one of thespatial codewords and on a difference between the first and secondreference CQI. 9PC. The process claimed in claim 9P wherein the CQIreport is derived using at least one of: 1) an entry index of a vectorcodebook, 2) a transform, 3) a parameterization.

14A. The MIMO wireless node claimed in claim 14 wherein the firstdifferential subbands CQI vector includes at least one difference of atleast one subband CQI in the second CQI vector pairwise relative to atleast one subband CQI in the first CQI vector. 14B. The MIMO wirelessnode claimed in claim 14 wherein the first differential subbands CQIvector includes a difference of at least one CQI for selected subbandsrelative to the first reference CQI, and the second differentialsubbands CQI vector includes a difference of at least one CQI forselected subbands relative to the second reference CQI.

14P. A process for operating a MIMO wireless node for multiple-input,multiple-output (MIMO), the process comprising receiving a signalcommunicating a channel quality indicator (CQI) report for first andsecond spatial codewords associated with a user equipment wherein theCQI report is derived from a first reference CQI and a first and asecond differential subbands CQI vector for each spatial codeword aswell as a differential between a second reference CQI and the firstreference CQI; and reconstructing a first and second subbands CQI vectorfrom said at least one signal associated with said CQI report. 14PA. Theprocess claimed in claim 14P wherein said reconstructing includesreconstructing the second reference CQI from both the first referenceCQI and the differential between the second reference CQI and the firstreference CQI. 14PB. The process claimed in claim 14PA wherein saidreconstructing further includes reconstructing the first subbands CQIvector for the first spatial codeword from the first differentialsubbands CQI vector and the first reference CQI, and reconstructing thesecond subbands CQI vector from the second differential subbands CQIvector and the reconstructed second reference CQI. 14PC. The processclaimed in claim 14P further comprising scheduling at least one userequipment based on said at least first and second reconstructed subbandsCQI vectors. 14PD. The process claimed in claim 14P further comprisingsending data streams to at least one scheduled user equipment. 14PE. Theprocess claimed in claim 14P wherein the first differential subbands CQIvector includes a difference of at least one CQI for selected subbandsrelative to the first reference CQI, and the second differentialsubbands CQI vector includes a difference of at least one CQI forselected subbands relative to the second reference CQI.

16A. The MIMO wireless node claimed in claim 16 wherein the CQI reportincludes information based on a first reference CQI for unselectedsubbands for a first spatial codeword and a second reference CQI forunselected subbands for a second spatial codeword, and said processingcircuitry is operable to determine at least one selected subband foreach spatial codeword and use the configurably established scanningpattern for processing the CQI report across the spatial codewords andeach selected subband.

16P. A process for operating a wireless node for multiple-input,multiple-output (MIMO), the process comprising receiving at least onesignal, each communicating a compressed channel quality indicator (CQI)report associated with a user equipment for spatial codewords andsubbands; and reconstructing at least a first and a second CQI vectorfrom said at least one signal according to a configurably establishedscanning pattern for processing the CQI report across the spatialcodewords and subbands wherein each reconstructed CQI vector isassociated with a plurality of subbands for each of at least first andsecond spatial codewords respectively. 16PA. The process claimed inclaim 16P further comprising scheduling at least one user equipmentbased on said at least first and second reconstructed CQI vector. 16PB.The process claimed in claim 16PA further comprising sending datastreams to at least one scheduled user equipment.

18A. The MIMO wireless node claimed in claim 18 wherein thereconstruction includes reconstruction from at least one of: 1) an entryindex of a vector codebook, 2) a transform, 3) a parameterization.

18P. A process for operating a wireless node for multiple-input,multiple-output (MIMO), the process comprising receiving at least onesignal, each communicating a channel quality indicator (CQI) reportassociated with a user equipment for at least first and second spatialcodewords and subbands, and reconstructing at least a first and a secondCQI vector, associated with subbands for each of the at least first andsecond spatial codewords respectively, from the CQI report includinginformation based on a vector differential between a second differentialsubbands CQI vector and a first differential subbands CQI vector for thespatial codewords respectively. 18PA. The process claimed in claim 18further comprising scheduling at least one user equipment based on saidat least first and second reconstructed CQI vector. 18PB. The processclaimed in claim 18PA further comprising sending data streams to atleast one scheduled user equipment. 18PC. The process claimed in claim18 wherein the reconstructing includes reconstructing from the CQIreport including information based on a said differential subbands CQIvector itself.

Notes: Aspects are paragraphs which might be offered as claims in patentprosecution. The above dependently-written Aspects have leading digitsand internal dependency designations to indicate the claims or aspectsto which they pertain. Aspects having no internal dependencydesignations have leading digits and alphanumerics to indicate theposition in the ordering of claims at which they might be situated ifoffered as claims in prosecution.

Those skilled in the art to which the invention relates will appreciatethat other and further additions, deletions, substitutions andmodifications may be made to the described embodiments without departingfrom the scope of the invention. Processing circuitry comprehendsdigital, analog and mixed signal (digital/analog) integrated circuits,ASIC circuits, PALs, PLAs, decoders, memories, non-software basedprocessors, microcontrollers and other circuitry, and digital computersincluding microprocessors and microcomputers of any architecture, orcombinations thereof. Internal and external couplings and connectionscan be ohmic, capacitive, inductive, photonic, and direct or indirectvia intervening circuits or otherwise as desirable. Implementation iscontemplated in discrete components or fully integrated circuits in anymaterials family and combinations thereof. Block diagrams herein arealso representative of flow diagrams for operations of any embodimentswhether of hardware, software, or firmware, and processes of manufacturethereof, and vice-versa. While the methods disclosed herein have beendescribed and shown with reference to particular steps performed in aparticular order, it will be understood that these steps may becombined, omitted, subdivided, or reordered to form an equivalent methodwithout departing from the teachings of the present disclosure.Accordingly, unless specifically indicated herein, the order or thegrouping of the steps is not a limitation of the present invention.Illustrative embodiments are not to be construed in a limiting sense. Itis therefore contemplated that the appended claims and their equivalentscover any such embodiments, modifications, and embodiments as fallwithin the true scope of the invention.

1-20. (canceled)
 21. A method of operating a user equipment to transmitchannel state information (CSI) feedback comprising: generating awideband channel quality indicator (CQI) for a first codeword torepresent a plurality of subbands; generating a wideband CQI for asecond codeword to represent a plurality of subbands; generating aspatial differential CQI which is a function of the first and secondwideband CQIs; and transmitting the wideband CQI value corresponding tothe first codeword and the spatial differential CQI.
 22. The method inclaim 21 wherein the spatial differential CQI is formed by computing anoffset level equal to the difference between the wideband CQI of thefirst codeword and the wideband CQI of the second codebook andquantizing the offset level according to Spatial differential CQI valueOffset level 0 0 1 1 2 2 3 ≧3 4 ≦−4 5 −3 6 −2 7 −1


23. The method of claim 21 wherein the CQIs are transmitted using aphysical uplink control channel (PUCCH).
 24. A user equipment,comprising: circuitry for generating a wideband channel qualityindicator (CQI) for a first codeword to represent a plurality ofsubbands; circuitry for generating a wideband CQI for a second codewordto represent a plurality of subbands; circuitry for generating a spatialdifferential CQI which is a function of the first and second widebandCQIs; and circuitry for transmitting the wideband CQI valuecorresponding to the first codeword and the spatial differential CQI.25. The user equipment of claim 24 wherein the spatial differential CQIis formed by computing an offset level equal to the difference betweenthe wideband CQI of the first codeword and the wideband CQI of thesecond codebook and quantizing the offset level according to Spatialdifferential CQI value Offset level 0 0 1 1 2 2 3 ≧3 4 ≦−4 5 −3 6 −2 7−1


26. The user equipment of claim 24 wherein the CQIs are transmittedusing a physical uplink control channel (PUCCH).
 27. A wireless nodethat transmits channel state information (CSI) feedback comprising: awideband channel quality indicator (CQI) for a first codeword torepresent a plurality of subbands; a wideband channel quality indicator(CQI) for a second codeword to represent a plurality of subbands; aspatial differential CQI that is generated as a function of the firstand second wideband CQIs.
 28. The wireless node in claim 27 wherein thespatial differential CQI is formed by computing an offset level equal tothe difference between the wideband CQI of the first codeword and thewideband CQI of the second codebook and quantizing the offset levelaccording to Spatial differential CQI value Offset level 0 0 1 1 2 2 3≧3 4 ≦−4 5 −3 6 −2 7 −1


29. The wireless node of claim 27 wherein the CQIs are transmitted usinga physical uplink control channel (PUCCH).